Presentation on theme: "An Inside Look at ANSI/ASHRAE/IESNA Standard"— Presentation transcript:
1 An Inside Look at ANSI/ASHRAE/IESNA Standard 90.1-2007 Energy Standard for Buildings Except Low-Rise Residential BuildingsIn late 2004 ASHRAE published its latest version of ASHRAE Standard 90.1 – Energy Standard for Buildings Except Low-Rise Residential Buildings.Prior to that, in June of 1999, the ASHRAE Standards Committee and ASHRAE Board of Directors approved ASHRAE Standard And in the fall of 2001, an updated version was published.We’ll discuss and point out some of the major changes between the 2001 and standards.Although we’ll touch on all subjects in the standard, our focus will be the HVAC section.Mick Schwedler, PE Manager Trane Applications Engineering Chair, SSPC 90.1
2 Help you gain a working knowledge of ASHRAE Standard 90.1 There’s no way we can cover the entire contents of ASHRAE 90.1 during our time together. Instead, the goal for today is to provide you with sufficient information to understand how it may affect you.If you have questions during the presentation, please feel free to ask them. If the answer will be covered on a later slide, I may ask you to postpone your query until then.
3 ASHRAE Standard 90.1-2007 Topics for Today’s Discussion Brief historyImplementationCodesU.S. military requirementsLEED® green building rating programContentsTitle, purpose, scopeAspects of building addressed by provisionsAn overview of today’s topics is shown here. We’ll look at how ASHRAE 90.1 came about and how various bodies have used the standard. After covering its Title, Purpose, and Scope, we’ll then spend most of our time on the sections of the standard.
4 ASHRAE Standard 90.1-2007 Brief history • Milestones • Plan for reprints• Scope of 2007 revisionLet’s look at where 90.1 began, the plant for its future, then the 2004 revision’s scope.
5 Historical Timeline 90.1-1999 major rewrite 90.1-2001 minor revisions updated1970updated1980199020002010first issuedupdates, reorganizationThe standard is sponsored jointly by the American Society of Heating, Refrigerating and Air- Conditioning Engineers, Inc. (ASHRAE) and The Illuminating Engineering Society of North America (IESNA).It was first published in 1975, partially in response to the oil embargo. However, ASHRAE and IESNA also felt that the national impact of energy conservation was important enough to keep the standard active. The standard was updated in 1980.In 1989, an updated version of the standard was published. We’ll touch on it briefly in just a moment.For almost 10 years a committee worked to rewrite ASHRAE 90.1 and this was designatedAt that point the standard was put on continuous maintenance. During following years revisions were made through the continuous maintenance process, resulting in a 2001 version and then , released in the fall of 2004.Updates
6 ASHRAE Standard 90.1 Publication Plan Last published in late 2007Future reprints at 3-year intervalsCoordinated with model building codesPrevious version plus all published addenda since last reprintplanned for BOD approval in June 2010At the June 2004 annual meeting in Nashville, ASHRAE’s 90.1 committee voted to approve the version for publication. It was printed late in 2004.Looking to the future, ASHRAE intends to reprint 90.1 every three years, in conjunction with the timing of model codes. Each time, it will be the previous standard, plus all published addenda.
7 ASHRAE Standard 90.1 2007 Changes from 2004 Incorporates 42 addenda published since was releasedBetween the 2001 and 2004 versions, there were 31 addenda published. All these addenda are included inSome major changes included changing the number of climate zones from 26 to 8 and significantly reducing the allowable lighting power allowances. We’ll look at these and other addenda in more detail later.In an attempt to make it more easily adopted into codes, the standard was reorganized and renumbered.
8 ASHRAE Standard 90.1 Scope of 2007 Update new inMarks a noteworthy change fromapplicationTIPMarks an application tip, not a standard requirementDuring the presentation, we’ll try to point out noteworthy changes by including a “New in ” circle on the slide.In some cases we’ll step away from the standard requirements to discuss how a designer might use system design or control to achieve or exceed the standard. When we do there will be an “application tip” circle on the slide.
9 ASHRAE Standard 90.1-2007 Implementation • Model codes • U.S. government• Outside U.S.• LEED® program
10 ASHRAE Standard 90.1 and Model Codes ASHRAE Standard 90.1 is adopted by:American National Standards Institute ( )National Fire Protection AssociationInternational Code Council (International Energy Conservation Code)In the fall of 2000, ASHRAE Standard became an ANSI code.Now we need to step back and understand a little more about codes.ASHRAE 90.1 is adopted by reference by the National Fire Protection Association, so if a locale adopts NFPA, it adopt ASHRAE 90.1.The International Code Council has also developed a single set of regulatory documents for use by states and other locales. One of the International Code documents is the International Energy Conservation Code.The 2000 edition of the IECC adopted ASHRAE Standard (the old version) by reference, while the 2004 IECC supplement uses ASHRAE StandardAt present, some states are updating their codes to adopt the 2004 IECC supplement; so let’s look at the IECC in a little more detail.
11 ASHRAE Standard 90.1 and Energy Codes International Energy Conservation Code (IECC)IECC–Chapter 8 adopts by referenceIECC–Chapter 7 describes an alternate path for complianceIncludes many provisions ofASHRAE is proposing code changes to increase stringencyAs we look at energy codes, is adopted by reference into the International Energy Conservation Code in Chapter 8.An alternative path in the IECC is to follow the provisions of Chapter 7, which includes many but not all of the requirements ofASHRAE has a Code Interaction Subcommittee that’s working with the 90.1 committee to determine changes ASHRAE should submit to the IECC Chapter 7 to increase its stringency – and bring more of into that portion of the IECC.
12 ASHRAE Standard 90.1 and State Energy Codes Asked DOE for extensionMeet or exceed , 2001, or 200490. 1 being considered(state bldgs)(voluntary)(July 1, 2005)(optional)The locales shown in gold on this slide have already adopted , 2001 or 2004 as their energy code. Most have done this through adoption of the IECC, although many have local changes. This list continues to grow.Others are moving forward from advisory groups that recommended adoption of They’re shown in green. As you can see, the number of states moving forward with updates is significant.If you are in one of the green states, you may wish to contact your local legislators to check on the status.
13 ASHRAE Standard 90.1 adoption by U.S. Department of Defense “2-1 MANDATORY ENERGY AND WATER CONSERVATION CRITERIA. Family housing (residential) shall be designed and constructed in accordance with the latest Energy Star standards, per other appropriate service-specific criteria and guidance. Other facilities shall be designed and constructed in accordance with the latest edition of ASHRAE Standard 90.1.”—Excerpt from Unified Facilities CriteriaOther groups are mandating use of ASHRAE 90.1, too.For example, in its Unified Facilities Criteria document, the U.S. Department of Defense requires that the “latest edition of ASHRAE Standard 90.1” be used in design of non-residential facilities. The link is shown here.Those of you working with any Department of Defense facilities will need to know about the latest edition of_UFC pdf
14 ASHRAE Standard 90.1 adoption Outside the U.S. Canada Similar or higher efficiency levelsChina Modifying for high local ambient wet bulbsUnited States ASHRAE StandardIn addition, 90.1 is being considered or revised as an energy code outside the U.S.In Brazil, a team working toward energy standards has done a study and recommended amendment of codes in Recife and Salvador. According to a member on the Brazilian committee, “We are using (in the city codes and in the Brazilian standard) the inspiration of ASHRAE 90.1 but not the limits proposed there as they are too stringent (high) for our building industry reality.”[Canada - Chiller requirements - Oct 28, 2004,China is considering modifying the part-load values for equipment because the ambient wet bulbs in many locations do not allow reduction of condenser water temperatures.[Mexico]Thailand has done a lot of study, especially with respect to the envelope. They’ve examined both and the Singapore code, and seem likely to develop energy requirements differing from those in 90.1.Thailand Major changes based on building envelope studiesBrazil Law (2004), Energy Efficiency Standards
15 ASHRAE Standard 90.1 and LEED®-NC Version 2.2 EAp2: Minimum energy performanceMandatory provisions of andPrescriptive requirements or 14% better thanEAc1: Optimize energy performanceAwards points for improving performance rating of the design building vs. baseline building at least 14% better thanLEED-NC version 2.2’s public review draft refers to ASHRAE NC 2.2 was expected to be sent to U.S. Green Building Council members in fall of 2005 for balloting.As you can see, there are many reasons for the interest in ASHRAE 90.1.
16 LEED NC 2009 : EAp2 Minimum energy performance Option 1: performance compliance pathMandatory provision (5.4, 6.4, 7.4, 8.4, 9.4, and 10.4)Baseline building complies with Appendix G Building PRM10% better than for new construction, 5% better for existing buildingOption 2: prescriptive compliance pathASHRAE AEDGsmall office buildings 2004small retail buildings 2006small warehouses and self-storage buildings 2008Option 3: prescriptive compliance pathAdvanced Buildings Core Performance Guide[SLIDE] In LEED NC 2009 for minimum energy performance, there are three options to comply with: one performance compliance path and two prescriptive compliance paths. We will examine each option as compared to NC 2.2 next.
17 EAC1 – Modeling Up to 19 points New BuildingsExisting Building RenovationsPoints12%8%114%10%216%318%420%522%624%726%828%930%1032%1134%1236%1338%1440%1542%1644%1746%1848%19[MICK] Remember that the prerequisite is now 10% less energy cost compared to ASHRAE for new construction and 6% for existing building renovations. In EA credit 1, optimizing energy, we can accrue points.[SLIDE] For new construction, at 12% energy cost reduction you achieve 1 point. For a renovation, 8% reduction allows 1 point to be achieved.Each additional 2% of energy cost savings accrues another credit point.Up to a maximum of 19 points can be achieved. Needless to say, there is significant emphasis on optimizing the energy within the project.Scott will help us examine ways these points can be achieved in a few minutes.
18 ASHRAE Standard 90.1-2007 Contents • Purpose • Scope • Aspects of building addressed by provisionsNow let’s get into the content of the standard.
19 ASHRAE Standard 90.1-2007 Purpose “… Provide minimum requirements for the energy- efficient design of buildings except low-rise residential buildings”Note that its purpose is to define minimum requirements … not state-of-the-art. ASHRAE published its GreenGuide, and is working on the second edition. That document goes beyond the energy efficiency requirements in the standard and gives guidance to owners and designers who want to save more energy.Key words on this slide are:Minimum requirements, which represent the worst building that can be designed and still comply with the standard.Energy-efficient design.Except, which we’ll discuss on the next slide..
20 ASHRAE Standard 90.1-2007 Scope New buildings and their systemsNew portions of buildings and their systemsNew systems and equipment in existing buildingsThe 2004 standard includes additions and alterations to existing buildings. This modification, first made in 1999, changed many people’s perception of the standard. People from BOMA (Building Owners and Manufacturers Association) and the National Multi-Family Housing Council were members on the committee and worked to help everyone understand the impacts of including additions and alterations.
21 ASHRAE Standard 90.1-2007 Exclusions Low-rise residential buildingsASHRAE Standard 90.2 covers low-rise (3 stories or less), one-family, and two-family residential buildingsBuildings that do not use electricity or fossil fuelEquipment and portions of building systems that use energy to support industrial, manufacturing, or commercial processesAlthough Standard 90.1 applies to high-rise condominiums, it does NOT apply to low-rise residential buildings. Standard 90.2 defines the performance requirements for low-rise residential buildings as well as for one- and two-family dwellings.Also excluded from 90.1 are buildings that don’t use fossil fuel or electricity.The final exclusion is for equipment and systems that are used primarily to support processes. For example, a chilled water system that serves manufacturing of plastics would be excluded from complying with 90.1 because it’s used to enable a process. However, if an HVAC conditioned a manufacturing plant and the people, then it would be covered under 90.1.Now that you know the purpose and scope of the standard, let’s step through its sections.
22 ASHRAE Standard 90.1 Sections Section 1: PurposeSection 2: ScopeSection 3: Definitions, Abbreviations, and AcronymsSection 4: Administration and EnforcementSection 5: Building EnvelopeSection 6: HVACSection 7: Service Water HeatingSection 8: PowerSection 9: LightingSection 10: Electric MotorsSection 11: Energy Cost Budget (ECB) MethodSection 12: Normative ReferencesAppendicesThere is a “Definitions” section in the standard. The definitions were compiled from various building codes, the ASHRAE Terminology Handbook, the IESNA Handbook, etc. Where appropriate, the SSPC modified some of these definitions and created new definitions for terms that weren’t found in these sources.As an example, the term “HVAC System” is defined as: “The equipment, distribution systems, and terminals that provide, either collectively or individually, the processes of heating, ventilation, or air conditioning to a building or portion of a building.”
23 Section 5: Building Envelope ASHRAE Standard 90.1Section 5: Building EnvelopeWe’ll now take a high-level look at the “envelope” section of the standard.
25 appendix B: building envelope Climate Criteria Groups climates into 8 zonesSubcategorizes zones by humidity level1 very hot2 hot3 warm4 mixed5 cool6 cold7 very cold8 subarticLook up climate zones by location …Miami, San Juan= 1ASeattle = 4CReykjavik = 7A change from previous versions of the standard, climates are now grouped into 8 zones (rather than 26), ranging from Zone 1 (very hot) to Zone 8 (subarctic).In addition to the climate zone numbers, locales are designated by their humidity, with A being moist, B being dry, and C being marine. An example of a marine climate is San Francisco because its climate is affected by the Pacific Ocean.Other examples of climates are shown on the slide.A moistC marineB dry
26 U.S. Climate Classifications (Briggs et al., 2002) Here’s a graphic showing U.S. climate zones.
27 ASHRAE Standard 90.1 More International Data For South America …Ascuncion Montivideo Belem Porto Alegre Brasilia Punta Arenas Buenos Aries Recife/Curado Caracas Rio de Janeiro Concepcion San Juan Cordoba de Marcona Fortaleza Santiago La Paz Sao Paulo Lima TalaraThe 2004 edition of ASHRAE Standard 90.1 also includes many weather locations outside North America. Here are those available for South America.
28 ASHRAE Standard 90.1 More International Data For Puerto Rico …All Zone 1A Except,Barranquitas 2 SSW - 2BCayey 1 E - 2BThe 2004 edition of ASHRAE Standard 90.1 also includes many weather locations outside North America. Here are those available for South America.
29 ASHRAE Standard 90.1 Compliance Paths: Envelope Prescriptive Building Envelope Option (§5.5)general & mandatory provisionsBuilding Envelope Trade-Off Option (§5.6, performance)90.1 provides several ways to comply with the envelope section. Many people will simply use the mandatory and prescriptive requirements of each section. Some designers may want to trade some of those prescriptive requirements. This is allowable using the Building Envelope Trade-off option or the Energy Cost Budget method.Using any of these paths results in an ASHRAE 90.1-compliant building.Energy Cost Budget Method (ECB, §11)proposed building design90.1-compliant building
30 Mandatory Provisions Labeling of insulation R-value Rating of doors and fenestrationAir leakageBuilding envelopeFenestration and doorsLoading docksVestibules (with exceptions)Mandatory provisions relate first to labeling of insulation R-Values as well as the rating and labeling of fenestration and doors. Fenestration includes all areas in the building envelope that let in light.There are also air leakage requirements for the envelope, for fenestration and doors, and for loading docks. Vestibules are required with exceptions such as hot climate zones 1 and 2, or doors opening directly from a dwelling unit.
32 section 5: building envelope Demonstrating Compliance Opaque elementsMaximum U-factor for entire assembly, orMinimum rated R-values of insulationFenestration …Maximum U-factorMaximum solar heat gain coefficient (SHGC)… based on orientation and percentageFor opaque elements such as roofs, walls, or exposed floors the assembly must either comply with the U-factor or an R value for insulation.Solar heat gain coefficients and U-factors for glass depend on the glass’s orientation and the amount of glass. A maximum of 50% glass is allowable using the prescriptive requirements.
33 prescriptive compliance Envelope Fenestration Skylight area as percentage of gross roof areaVertical fenestration glazing area as percentage of gross wall areaU-factor depends on construction typeSolar heat gain coefficient (SHGC) depends on orientationThe thought is that the user has some idea of window or skylight area percentage that he or she wishes to use.Given the percentage, the window type (fixed or operable) and orientation (north or all others), the U- factor and SHGC are determined.Prescriptively, the user may have up to 50% window area and up to 5% skylight. Above those numbers, the ENVSTD program (the building trade-off option) must be used.For example, you may install glass with lower solar heat gain coefficients and/or U-factors so you can use more glass. To do this you’d use the ENVSTD program.In the previous standard there were some common problems when dealing with fenestration:Performance ignored the effect of edge-of-glass and frameCorrect calculations were time-consumingFenestration wasn’t labeled in the field for the inspectorsFenestration solutions in :Specify National Fenestration Rating Council (NFRC) standardsCompliance verified by label on product
34 prescriptive compliance Opaque Envelope Elements No calculations required …Either:Specify insulation R-valueorLook up common U-factorsOpaque envelope elements include:RoofsWalls above gradeWalls below gradeFloorsSlab-on-grade floorsOpaque doorsFor a given location (climate), all one needs to do is to either put in the insulation R-value required or U-factor required. There are also tables of U-factors for commonly used walls. This way it is much easier to comply with the requirements.
35 overall U-factors Roof Construction Classes Insulation entirely above deckMetal building roofsAttic and other roofsThe types of roofs that can be easily considered are shown on this slide …
36 overall U-factors Above-Grade Walls Mass wallsMetal building wallsMetal-framed wallsWood-framed and other walls… And the prescriptive wall types are shown here.
37 Envelope Addenda as: Modifies opaque envelope requirements ChangeEnvelope Addendaas: Modifies opaque envelope requirementsat: Modifies fenestration (glass) requirementsSignificant changes were made to the envelope section of Both the opaque elements – walls, roofs, doors, etc. and the fenestration (glass) requirements changed and generally became more stringent. This means that heat conduction loads and solar loads should be reduced.
41 section 5: building envelope Demonstrating Compliance In lieu of prescriptive options….Building Envelope Trade-Off Option, orEnergy Cost Budget methodStill in conjunction with mandatory requirementsBuilding Envelope Trade-Off Option— EnvStd 5.0 software automates Envelope Performance Factor calculationsThere are some designs that will fall outside of the prescriptive option.There’s a procedure for calculating an “envelope performance factor” that’s been implemented in a computer program called ENVSTD 5.0. The software is distributed with the 90.1 User’s Manual.The purpose of this tradeoff is to allow greater flexibility for projects otherwise unable to demonstrate compliance via the prescriptive method. For example, you may use more glass than allowed prescriptively if the additional energy is offset by choosing glass with a better solar heat gain coefficient and U factor.The final path uses the energy cost budget method which is a computer simulation. We’ll discuss this in more detail later.As in other portions of the standard, whether the prescriptive, Building Envelope Trade-off Option, or Energy Cost Budget method is used, the mandatory requirements must still be met.
43 Section 6: HVAC Section 7: Service Water Heating ASHRAE Standard 90.1Section 6: HVACSection 7: Service Water HeatingMost of this presentation deals with the mechanical sections of 90.1.
44 ASHRAE Standard 90.1 Compliance Paths: HVAC prescriptive requirements (§6.5)mandatory provisions (§6.4)Energy Cost Budget Method (ECB, §11)Simplified Approach Option (§6.3)HVAC section provides three different paths for compliance. We’ll discuss each of them in some detail, beginning with the Simplified Approach Option for small buildings.Simplified Approach Option (§6.3)proposed HVAC design90.1-compliant HVAC system(small buildings only)
45 HVAC compliance with Std 90.1 Simplified Approach Minimal effortEqually stringent requirementsFits on two pagesLimited to …Buildings with 1 or 2 storiesBuildings less than 25,000 square feetSingle-zone systemsAir-cooled or evaporatively cooledThe Simplified Approach was included so that a small building could comply with the standard with minimal effort, but be subjected to the same stringency as is in the rest of the standard.The goal was to fit the requirements for this type of building on about two pages.The simplified approach is restricted in size (25,000 square feet) and use. The building must be two stories or less, and the system must serve a single HVAC zone — for example, the face of a building. Minimum equipment efficiency is still a requirement. It must also be air-cooled. An example would be a single-zone rooftop. You may have multiple zones within a building.
46 HVAC compliance with Std 90.1 Simplified Approach continuedEconomizer as necessaryHeat: Heat pump, fuel-fired furnace, electric resistance, or baseboard system with boilerOutdoor air: ≤ 3,000 cfm, < 70% of SA, unless energy recovery is usedManual-changeover or dual-setpoint thermostatControls for heat pumps with auxiliary heatNo reheat for humidity controlThis approach also defines limits which, when exceeded, necessitate economizers, certain control options, piping insulation, etc.All of these requirements will be covered in detail when we review the mandatory and prescriptive portions of the standard.
47 HVAC compliance with Std 90.1 Simplified Approach concludedNight setback controls (except hotel/motel guest rooms)Insulation for piping and ductworkBalancing of ducted systemsInterlocked thermostats for separate heating and cooling equipmentExhaust > 300 cfm: Gravity or motorized dampersSystem > 10,000 cfm: Optimum startSystem balancing is required and the thermostatic controls must be interlocked to prevent simultaneous heating and cooling.Please understand that if you went through the entire standard, you would arrive at the same requirements for this system type. The Standard 90.1 committee was able to condense the requirements for these small buildings to fit on about a page and a half.
48 section 6: HVAC Mandatory Provisions prescriptive requirements (§6.5)mandatory provisions (§6.4)Energy Cost Budget Method (ECB, §11)Simplified Approach Option (§6.3)Let’s step through the next possible path – mandatory plus prescriptive requirements.Mandatory requirements are just that—mandatory. They cannot be traded off.Simplified Approach Option (§6.3)proposed HVAC design90.1-compliant HVAC system(small buildings only)
49 section 6: HVAC Mandatory Provisions Equipment efficienciesLoad calculationsControlsConstruction and insulationCompletion requirementsDrawings, manuals, balancing, and commissioningThe standard’s mandatory requirements address the subjects shown here. Both the prescriptive and the ECB compliance “paths” must meet these requirements.
50 mandatory HVAC provisions Equipment Efficiencies Air conditioners and condensing unitsHeat pumpsChillersPTACsFurnacesBoilersHeat-rejection equipmentShown here are several of the HVAC equipment types with minimum requirements in the standard. There are efficiency tables for each type of equipment.It’s important to understand that pieces of equipment that are not listed have NO requirements. For example, there are no testing standards in place for engine-driven chillers. Since they aren’t rated and tested, the committee did not include requirements for them in the standard. But this doesn’t mean that engine-driven chillers can’t be used.
51 section 6: HVAC Equipment Efficiencies raised Changesection 6: HVAC Equipment Efficiencies raisedan: Boiler efficiencies 18 trillion Btu of gas or oil annually as stock turnsF: Three-phase air-cooled AC and heat pumps 2.3 quads by 2035g: Air-cooled AC and heat pumps quads by 2035In the mechanical section, equipment efficiency increases occurred for Boilers, three-phased air-cooled air conditioners and heat pumps, and air-cooled air conditioners and heat pumps. The SSPC attempted to estimate the savings based on implementation of each addendum. The estimates shown on the slide are taken from the forewords of each addendum.
52 examples of Equipment Efficiencies Equipment type Minimum efficiencySelf-contained, water-cooled EER w/electric resistance heat IPLV (20–100 tons)Water-source heat pump EER (cooling) (1.5–5.25 tons) COP (heating)Centrifugal chiller, COP kW/ton water-cooled ( 300 tons) IPLV IPLV (at ARI rating conditions)This slide gives three examples of required equipment efficiencies.The column shown is the efficiency requirement. Note that for the chiller, this is a COP of 6.10 ( kW/ton) (at ARI standard rating conditions) as of 10/29/2004.It’s also important to note that the standard states if there is more than one requirement, all must be met. Self-contained units and chillers must meet both full-load and part-load requirements and heat pumps must meet both cooling and heating requirements.To make sure it’s understood -- These equipment efficiencies are mandatory, whether the prescriptive or ECB method of compliance is used. Equipment efficiencies CANNOT be traded off against other aspects of the building.While Mick Schwedler from Trane was active on the 90.1 committee, we also want to acknowledge that Rich Ertinger from Carrier and Safir Adeni from York did a great job of representing the industry during the adoption of these efficiency requirements in the 1999 standard. All three:Worked hard to develop a good standardDid not attempt to help their companies gain competitive advantageSupported the standard’s approval.Presently Carrier, York, McQuay, and Trane—as well as ARI—are represented on the 90.1 committee. Trane’s representative is Susanna Hanson.§ : “… Where multiple rating conditions or performance requirements are provided, the equipment shall satisfy all stated requirements …”
54 mandatory HVAC provisions Zone Thermostatic Controls Required for each zonePerimeter can be treated differently≥5º F deadbandDual setpoint or deadband (can be software for DDC)There is also a mandatory section on controls.Thermostatic controls are required for each zone (not room, but thermal zone), although the perimeter can be treated differently (as we’ll see on the next slide).There is also a requirement for a 5°F deadband, which is the difference between when cooling starts place and when heating starts.As with most portions of the standard, there are exceptions. For example, this deadband is not required in places such as retirement homes.By the way, because our time is limited, this presentation won’t cover all the exceptions in the standard. But it does include those that are most likely to be used.
55 zone thermostatic controls Perimeter Zones building plan view: thermal zoning exampleZ1Core and each long exposure must be zoned separatelyZ5Z4Z2< 50 ftThe 90.1 User’s Manual gives a very good example of how the perimeter may be zoned. The “definitions” chapter also discusses what constitutes a zone—especially on the perimeter. In the example, as long as there is less than 50 feet of contiguous exposure in one direction, a separate zone is not required.I do suggest that you purchase the 90.1 User’s Manual. It covers the committee’s intent and gives some great examples.Treating these exposures as a single zone is okayZ360 ft
56 ChangeOff-hour ControlsException was deleted for HVAC systems serving hotel/motel guest roomsIn the controls section of 90.1 an exception that used to exclude hotel and motel guest rooms from the off-hour control requirements was deleted.
57 mandatory for systems ≥ 15,000 Btu/h Automatic Shutdown Automatic 7-day/week time clock with 10-hour battery backupException: 2-day/week thermostat for residential applicationsOccupancy sensorManually operated timer (maximum duration: 2 hours)Security system interlockOnce the system exceeds 15,000 Btu/h, a number of off-hour control requirements become applicable. In the 2001 version of the standard, this requirement only kicked in if the system was above 65,000 Btu/h AND if the fan motor was larger than ¾ hp.The standard states that at least one of the off-hour control strategies listed on the slide must be available. Anecdotally, we’re seeing more applications with occupancy sensors.Notice the exception for residential applications, which only requires that the thermostat provide two different time schedules per week.
58 mandatory for systems ≥ 15,000 Btu/h Setback Controls Climate zones 2-8: Lower heating setpoint to 55°F or lessClimate zones 1b, 2b, 3b (hot/dry): Automatically restart, temporarily operateRaise cooling setpoint to 90°F or higherOrPrevent high space humidity levelsRequirement for setback also changed from the 2001 version of In the 2004 version:Heating setback is required in most climate zones.Cooling setback is required only in hot, dry climate zones and must be automated.
59 mandatory HVAC provisions Other Off-Hour Controls Provide optimum start if system supply- air capacity > 10,000 cfmZone isolation:25,000 ft² maximum zone size on one floorIsolation devices to shut off outdoor and exhaust airflowCentral systems capable of stable operationOptimum start is required to start the heating and cooling systems as late as possible and still meet the setpoint. As a minimum, the control algorithm needs to be a function of the difference between the space temperature and occupied setpoint, and the amount of time prior to scheduled occupancy.Optimum start is required once the system is greater than 10,000 cfm.During off-hours, the system must be capable of reducing airflow. This is so that the entire air- conditioning system doesn’t have to function to satisfy a small area of the building.It’s also necessary to be able to operate in a stable manner at these reduced airflows.
61 ASHRAE 62.1 Reference Changed from 62.1-1999 to 62.1-2004 Ventilation rates changedNow based on summation of rates per person and per areaWhile a fairly small change in the text of the standard, the reference to ASHRAE Standard 62.1, Ventilation for Acceptable Indoor Air Quality, changed from the 1999 version to the 2004 version.So addenda that changed standard 62.1 are now used to define the minimum requirements of also. As discussed on previous broadcasts, the addenda changed ventilation requirements and for each zone the requirement is based on the sum of a per person, and per square foot requirements.Please refer to the engineers Newsletters in the bibliography for more information.
62 mandatory HVAC provisions Ventilation System Controls Provide motorized dampers:In stair and elevator shaftsOn gravity hoods, vents, and ventilatorsExceptions:Buildings < 3 stories highOr, any building in climate zones 1,2,3 (hot climates)Ventilation systems serving unconditioned spacesTo help control building pressure, motorized dampers are required in stair and elevator shafts.Also, gravity hoods, vents and ventilators are required to have motorized dampers unless one of the exceptions is met.
63 mandatory HVAC provisions Ventilation System Controls Provide shutoff-damper control for outdoor-air supply and exhaust systemsAutomatically shut when systems or spaces are not in useAutomatically shut during building warm-up, cool-down, and setbackExceptions:Buildings < 3 stories high, or any building in climate zones 1,2,3Outdoor-air intake or exhaust < 300 cfmShutoff-damper control for outdoor air supply and exhaust systems must include motorized dampers unless the application meets one of the exceptions. The dampers must be capable of automatically shutting off outdoor airflow when the spaces are not in use; or during warm-up, cool-down, or setback when ventilation is not required.
64 mandatory HVAC provisions Damper Leakage Rate Maximum leakage at 1.0 in. wg, cfm/ft² of damper areaClimate zone Motorized Non-motorized1, 2, 6, 7, cfm/ft² Not allowedAll others 10 cfm/ft² 20 cfm/ft²*Allowable damper leakage rates are dependent on the climate and whether the dampers are motorized or non-motorized. Remember that some applications require motorized dampers, so if they are in either cold or hot climate zones, the allowable leakage rate is only 4 cfm per square foot of damper area.* Dampers < 24 inches in either dimension may have leakage of 40 cfm/ft²
65 mandatory HVAC provisions Ventilation: High Occupancy Changemandatory HVAC provisions Ventilation: High OccupancyDemand Control Ventilation (DCV) required for Spaces > 500 ft2 and design occupancy > 40 people/1000 ft²:(was 3000 cfm and 100 people/1000 ft2)On our last ENL broadcast we spent quite a bit of time covering demand controlled ventilation.The threshold for which DCV is required for a space was reduced and now applies if the space is more than 500 square feet and the design occupancy is greater than 40 people per thousand square feet.
66 mandatory HVAC provisions Heat Pumps: Auxiliary Heat For heat pumps with internal electric heaters, controls must lock out electric heat when load can be met by heat pump aloneException: Heat pumps regulated by NAECA if HSPF rating meets Table 6.8.1B and includes electric resistance heatingIf a heat pump with internal electric heaters is used, the first source of heat must be the heat pump, rather than the resistance heat. This is because the COP of a heat pump can be in the range of 3 or higher.Exceptions are for NAECA equipment and where the rating already includes the electric resistance heating.
67 mandatory HVAC provisions Humidification Controls Humidifier preheatShut off humidifier preheat when humidification is not requiredHumidification and dehumidificationPrevent simultaneous operationException: Spaces that require specific humidity levels (computer rooms, museums, hospitals) if approved by authority having jurisdictionIf humidifiers have preheat, the preheat function must be disabled when humidification is not required.In addition, controls that prevent simultaneous humidification and dehumidification are required. There are exceptions for applications, such as those shown on the screen.
68 mandatory HVAC provisions Ventilation: High Occupancy If outdoor air > 3,000 cfm and design occupancy > 100 people/1000 ft²:Automatically reduce outdoor air intake below design requirements when spaces are partially occupiedExceptions:Systems with exhaust-air energy recovery complying with SectionSystems with < 1,200 cfm outdoor airIn spaces that have more than 3000 cfm and high occupancy, the system must be able to automatically reduce outdoor-air intake when the spaces are partially occupied.However, this is not required if airside energy recovery is employed. We’ll look at that energy-recovery requirement in a few minutes.
70 mandatory HVAC provisions Construction & Insulation Insulation must be suited to environmentDuct, plenum insulationClimate zoneLocationPiping insulationHeating, domestic hot water, or coolingTemperaturePipe sizeThere are specific requirements for insulation. Basically the insulation needs to be able to hold up to its environment. If it’s outside, it must hold up to the sun, etc.The amount of insulation required depends on the climate, as well as whether the duct is outdoors, in a ventilated attic, conditioned space, etc.Piping insulation depends on whether it’s for heating or cooling, the fluid operating range, and the pipe size.
72 Construction and Insulation Must leak-test ductwork if design static pressure > 3 in. wgLeakage tests are required on duct systems where the static pressure is intended to operate in excess of 3 in. w.g.This will likely lead design engineers to reduce the static pressure in the ductwork to these levels or lower.
73 mandatory HVAC provisions Completion Requirements Documentation within 90 days of system acceptance:Drawings of actual installationSubmittal dataOperation and maintenance manualsService agency informationControl sequences and schematicsIt’s important that the design team’s knowledge and intent actually passes to the building owner. To that end, compliance with the standard requires that the owner receive the system drawings, manuals, and a narrative of intended operation within 90 days of acceptance.In addition, the name and address of at least one service agency must be given to the owner.If you think of it, this information should be provided on all jobs.There are also balancing requirements that must be met …
74 mandatory HVAC provisions Completion Requirements continuedSystem balancingWritten report conditioned spaces > 5000 ft²For airside system fan power > 1 hp and hydronic pumps >10 hp:1. Minimize throttling losses2. Trim impeller or adjust design speedBalancing is required once the conditioned space is greater than 5000 square feet. This is to be done in accordance with generally accepted engineering standards.The balancing requirements take effect if the airside is greater than 1 hp or the waterside is greater than 10 hp.Hydronic systems must be balanced first to minimize throttling losses, such as partially closed balancing valves, and then to trim the impeller or adjust the pump speed.
75 mandatory HVAC provisions Completion Requirements concludedCommissioning (Appendix E)Control elements calibrated, adjusted, and in working orderDesigner must provide detailed instructions (per Appendix E) for projects > 50,000 ft²Exceptions: Warehouses, semi-heated spacesCommissioning as used here is to make sure the system is calibrated, adjusted, and working properly. If the HVAC system serves an area larger than 50,000 square feet, it is the designer’s responsibility to provide detailed instructions.Some commissioning references are included in Appendix E of the standard.
76 section 6: HVAC Mandatory Provisions Recap Must be met whether using prescriptive or performance (ECB method) pathMandates include:Equipment efficiencyControlsConstruction and insulationCompletion requirements (drawings, manuals)Balancing and commissioningTo reiterate, we’ve covered the mandatory requirements in Section 6. In addition to these, one also must comply with the prescriptive requirements or use the Energy Cost Budget method.Remember, in either case, the mandatory requirements are exactly that—mandatory. Again, the mandatory requirements include:Equipment efficiencyControlsConstruction and insulationCompletion of drawings and manualsBalancing, andCommissioning
77 section 6: HVAC Prescriptive Requirements mandatory provisions (§6.4)Energy Cost Budget Method (ECB, §11)Simplified Approach Option (§6.3)Now that we’ve addressed the mandatory provisions, let’s move on to the prescriptive requirements ofSimplified Approach Option (§6.3)proposed HVAC design90.1-compliant HVAC system(small buildings only)
78 section 6: HVAC Prescriptive Requirements EconomizersSimultaneous heating and coolingAir system design and controlHydronic system design and controlHeat rejection equipmentEnergy recoveryExhaust hoodsRadiant heatingHot gas bypass limitationIf you want to use the prescriptive path, all prescriptive requirements must be met. Here’s a thumbnail sketch of what’s entailed:Requires economizers in specified climatesLimits how much simultaneous heating and cooling can be doneRestricts fan power based on nameplate horsepowerProvides specifications for hydronic system design and controlStates heat-recovery requirements for systems with large amounts of outdoor airNow let’s look at each of these sections.
79 prescriptive HVAC requirements Economizers Climate and system size determine need for an economizerMay be either airside or watersideNumerous (9) exceptions, including an efficiency tradeoffControl must be integrated with mechanical coolingOperation must not increase heating energy consumptionEconomizers are not required in all climates. In fact, the requirement is both size- and climate- dependent. We’ll look at them in a second.Remember that climates go from hot (1) to cold (8), and are moist (A), dry (B), or marine (C).When an economizer is required, it may be either an air or water economizer – at the discretion of the building owner and design teamThere are numerous exceptions including:Systems with condenser heat recoverySystems that operate less than 20 hours per weekSupermarket systemsWhere equipment efficiency has been increased to a level listed in the standard. This increased efficiency is intended to offset the reduced cost of cooling by the economizer.Control of the economizers must be integrated so that mechanical and economizer cooling can take place simultaneously.In all cases, the economizer must not increase the heating energy in the system. In effect, this disallows systems, such as single-fan double-duct, because they can greatly increase the heating energy usage. However, these systems could be used in locations that do not require economizers.
80 climate and system size determinants Economizers Cooling capacity for which an economizer is requiredClimate zone1a, 1b, 2a, 3a, 4a Economizer unnecessary (Puerto Rico, Miami, St. Louis, Charlotte)Here’s a chart that shows the various climate and system size combinations that require an economizer.By way of example, the chart also identifies several cities in each of the climate zone groupings.These economizer requirements are simpler than in the previous version of the standard.2b, 5a, 6a, 7, 8 ≥ 135,000 Btu/h (Yuma, Chicago, Edmonton)3b, 3c, 4b, 4c, 5b, 5c, 6b ≥ 65,000 Btu/h (Denver, Lubbock, Vancouver)
81 prescriptive HVAC requirements Air Economizers Prohibited control typesFixed enthalpy in climate zones 1b, 2b, 3b, 3c, 4b, 4c, 5b, 5c, 6b, 7, 8Differential dry bulb in climate zones 1a, 2a, 3a, 4aHigh-limit shutoff control settingsAble to relieve excess outdoor airIf an air economizer is selected, there are further stipulations in the standard.First, there are control-type prohibitions for specific climates. For example, differential dry-bulb control is not allowed in warm humid climates.Also, high-limit shutoff control settings are specified. For example, in Phoenix (a hot, dry climate) the economizer must shut off when the outdoor air temperature exceeds 75°F.The system also must be designed to allow relief of the additional outdoor air brought in by the economizer.
82 prescriptive HVAC requirements Water Economizers Capacity: 100% of system cooling load at 50°F DB/45°F WB (45°F DB/40°F WB for dehumidification)Maximum pressure drop < 15 ft (or bypassed) when not in usewaterside economizerIf a waterside economizer is chosen, there are sizing requirements to satisfy the building load when outdoor air conditions are 50°F DB/45°F WB. If dehumidification can’t be accomplished, ambient conditions of 45°F DB and 40°F WB may be used.If the waterside coil pressure drop is ≥ 15 feet, the economizer must be bypassed when it’s not being used.The 90.1 User’s Manual shows a diagram of the economizer in the sidestream or series location. In this position, it sees the warmest system water temperatures. Therefore, it is more effective and can be used for more hours of the year.It also allows the economizer to be integrated into the mechanical cooling system, and allows bypass when the economizer isn’t being used.Figure 6-O from 90.1 User’s Manual
83 prescriptive HVAC requirements Simultaneous Heating–Cooling Zone controlsNo reheatingNo recoolingNo mixing or simultaneously supplying mechanically (or economizer) cooled and mechanically heated airExceptions based on zone airflowThere are limits on simultaneous heating and cooling. Note that reheating or recooling (in the case of a desiccant system) is NOT banned since there are exceptions based on zone airflow. We’ll look at those on the next slide.
84 simultaneous heating–cooling Zone-Control Exceptions Zone airflow does not exceed whichever is largest:ASHRAE Standard 62’s zone requirements for outdoor air0.4 cfm/ft²30% of supply air300 cfmASHRAE Standard 62’s multiple-space requirementsFrom an airflow perspective, before reheating or recooling can be performed using new energy, the supply airflow in the zones must be reduced to the largest of the quantities shown here. One of the changes between the 1999 and 2004 versions is that the 30% exception was added.Many variable volume systems can be designed and operated to comply with one of these airflow limits. However, a constant volume system will have a tougher time meeting one of these exceptions.
85 simultaneous heating–cooling Zone-Control Exceptions concludedZones with special pressurization requirementsZones with code-required minimum circulation ratesSite-recovered or site-solar energy provides ≥ 75% of reheat energyThe restriction on simultaneous heating and cooling does not apply to zones with special pressurization requirements or code-required minimum circulation rates. An example is that some local health codes require a minimum circulation rate in hospital patient rooms.You may do any amount of reheating if at least 75 % of the reheat energy is site-recovered or site- solar.
86 prescriptive HVAC requirements Simultaneous Heating–Cooling Hydronic system controlsThree-pipe: Not allowedTwo-pipe changeover: Controls must prevent changeover unless …Outdoor dry bulb changes by ≥ 15°FSystem operates in one mode at least 4 hoursDifference between cooling and heating temperatures is ≤ 30°FHydronic systems also have requirements concerning simultaneous heating and cooling.The first is that three-pipe systems (cold supply, hot supply, and common return) are not allowed.In a two-pipe system, all of the following control requirements must be met:Before changing from one mode to another, the outdoor temperature must change by at least 15°FOne mode of operation must take place for 4 hours prior to changing to the other.When changeover occurs, there must be no more than a 30°F difference between the heating and cooling supply temperatures. For example, if 50°F cooling water is used, the initial heating water temperature must be 80°F or less before changeover takes place.
87 prescriptive HVAC requirements Simultaneous Heating–Cooling Hydronic (water loop) heat pump systemsDeadband ≥ 20°F (Exception: Optimized loop control)Climate zones 3-8:Bypass for closed-circuit fluid coolerIsolate open towers from heat-pump loopFor hydronic heat-pump systems, there must be a 20°F deadband between the control points for when the tower begins rejecting heat from the loop and when the boiler begins adding heat to the loop. This requirement is waived if the system uses an optimal loop controller.If a closed-circuit tower is used in climate zones 3-8 (colder), there must be bypass available so that the tower can be bypassed when no heat is being rejected.If an open-circuit tower is used with a heat exchanger, the cooling tower pump should be shut down when heat is not being rejected.
88 prescriptive HVAC requirements Simultaneous Heating–Cooling DehumidificationPrevent:ReheatingMixing of hot and cold air streamsHeating and cooling the same air streamIt also makes sense to reduce the amount of reheat when humidistatic controls are used. As in “normal” or comfort cooling reheat, there are a number of exceptions.
89 simultaneous heating–cooling Dehumidification Exceptions Reducing supply airflow to 50%, or minimum ventilation rateSystems < 6.67 tons that can unload at least 50%Systems smaller than 3.3 tonsSystems with specific humidity requirements (museums, surgical suites)75% of reheat/recool energy is site- recovered or site-solarHere they are. The amount of cooling must be reduced prior to reheating. These exceptions cover VAV systems, Systems that have multiple stages of unloading and small units.Also excepted are humidity-sensitive applications include computer rooms, museums, surgical suites, supermarkets and ice arenas.Again, reheat may be done at any time if 75% of the reheat energy is site-recovered or site-solar.
90 sidestream chiller arrangement Waterside Heat Recovery applicationTIPproduction (supply)bypass linedistribution (demand)While not a portion of the standard, it’s very likely that the limitations on simultaneous heating and cooling just discussed will lead to more designs that use either hot-gas reheat (in the case of a DX system) or heat recovered from a chiller’s condenser to satisfy “reheat” or “tempering” loads.Remember that when tempering, the required water temperature generally can be reduced—perhaps to °F—and still meet the load.Shown here is one method of piping a chiller into the system so that it can be preferentially loaded to provide as much recovered heat as possible.The recovered heat in this system comes from a chiller that is smaller than the rest of those in the system. Often it is best to size the heat recovery chiller to provide a portion, but not all, of the required heat.More information on this subject is available in Trane’s Waterside Heat Recovery application manual (SYS-APM005-EN).heat-recovery chiller
91 prescriptive HVAC requirements Simultaneous Heating–Cooling Humidification:If the hydronic cooling system requires an economizer …And if humidity of > 35°F DP must be maintained …Then the economizer must be watersideAnother requirement is in force if the building is humidified and if the humidification system is designed to maintain the inside humidity above 35°F DP. In this situation, if an economizer is required, it must be a waterside economizer.Many health-care facilities fall under this requirement.
92 prescriptive HVAC requirements Air System Design & Control Changeprescriptive HVAC requirements Air System Design & ControlFan system power limitation:Applies to systems > 5 hpOption Constant volume Variable volume1) Nameplate hp hp ≤ CFMs x hp ≤ CFMs x2) System bhp bhp ≤CFMs x A bhp ≤CFMs x AThe fan power limitation in Standard are now based on either nameplate horsepower, or system brake-horsepower with the limits shown on the slide. This was done in response to feedback from design engineers.
93 Fan Power Limitation Pressure Drop Adjustment ChangeFan Power Limitation Pressure Drop AdjustmentA = Σ (PD x CFMdesign / 4131)PD specified forDuctsFiltersGas-phase air cleanersHeat recovery devicesSound attenuation sectionsOther devicesIn addition, the standard also defines specific pressure drops that are allowed for a given device in the system. For example, MERV 13 filters are allowed 0.9 inches of pressure drop.This addendum has been received well by practitioners.
94 prescriptive HVAC requirements Air System Design & Control Changeprescriptive HVAC requirements Air System Design & ControlVAV fan controlMotors ≥ 10 hp require one of the following:Variable-speed driveVaneaxial fan with variable-pitch bladesDesign wattage ≤ 30% at 50% air volumeDDC systems must include setpoint reset (fan-pressure optimization)(was 15 hp)There have been requirements for technology to reduce part load fan energy use in the standard for quite sometime. The threshold for variable speed drives, or another technology that gives similar performance was reduced from 15 horespower to 10.
95 Fan-Pressure Optimization communicating BASVAV damper positionduct pressureFan-pressure optimization looks at all damper or valve positions and resets the supply fan’s static- pressure setpoint to maintain the damper needing the most pressure at a position that’s almost entirely open. This can drastically reduce the fan’s energy consumption.
96 fan-pressure optimization Control Logic applicationTIPIncrease static pressure setpoint75%Damper position (% open) of critical VAV boxNo actionThis graphic shows the simple control logic. If the system controller senses that all VAV dampers in the system are less than 85 percent open, it lowers the fan speed to reduce duct pressure. Since the VAV terminals are pressure-independent, they’ll open to maintain the same airflow. If any terminal is 95 percent open or more, the supply duct pressure is too low, and the control system will adjust the fan to increase the duct static pressure.In addition to the obvious fan energy savings, this method assures that zones cannot be starved for air. There are also significant acoustical benefits at part load by operating the fan and VAV terminals at the lowest possible duct pressure.This concept is covered in detail in the 1991, Volume 20, No. 2 Engineers Newsletter titled “VAV System Optimization: Critical Zone Reset.”Remember that fan-pressure optimization is required on DDC-VAV systems.65%Reduce static pressure setpoint
97 prescriptive HVAC requirements Hydronic System Design & Control These provisions apply if pump system power > 10 hp:Must be variable flow unless …Pump power ≤ 75 hp≤ 3 Control valvesLimit demand of individual variable-flow pumps to 30% of design wattage at 50% flow (e.g., use VSD)Pump head > 100 ftMotor > 50 hpNow, let’s look at pumping systems.Once pump system power is above 10 hp, a number of hydronic system design and control requirements kick in.Variable flow is required in large hydronic systems having more than three control valves.Individual, variable-flow pumps are required on high-head, high-power pumps.In these systems, the pump must operate at substantially less power draw at part load. Most likely, this will prompt designers to use variable-frequency drives.The pump may be controlled either by a pressure differential signal or as a function of flow—similar to the fan-pressure optimization already mentioned.
98 prescriptive HVAC requirements Hydronic System Design & Control Pump isolation (Series chillers “1 chiller”)Chilled and hot water reset > 300,000 Btu/h unless:Improper operation resultsSystem is variable flowTwo-position shutoff valve for heat pump system > 10 hpBasically, the “pump isolation” requirements say that pumping flow (and power) should be reduced when a chiller is turned off. The same is true for boilers.If chillers are piped in series, they are considered to be one chiller for this application.Chilled water reset is required, but not for variable-flow systems (where it doesn’t make sense) and not if improper operation (such as poor dehumidification) would result.Heat pump systems must include two-position valves if the hydronic system’s pump power is > 10 hp.
101 prescriptive HVAC requirements Heat-Rejection Equipment Fan speed controlMotors ≥7.5 hp must be able to operate at 2/3 of full speed or lessExceptions:Condenser fans serving multiple circuits or flooded condensersInstallations in climate zones 1 and 2Up to 1/3 of the fans on a multiple-fan application (if lead fans meet speed control requirement)When cooling tower fans are 7.5 hp and above, you must have the capability to reduce fan speed. Today, usually people use variable-speed drives on their tower fans.There are several exceptions. For example, if you’re in a hot climate (zones 1 or 2). Also, if the tower has three cells, at least two of them must be equipped with pony motors, half-speed control, or VFDs.
102 chiller–tower optimization Use of Fan Speeds applicationTIP1200Shaded areas = Optimal setpoint1550 tons: 65°F WB10008001160 tons: 59°F WBchiller plant power, kW600730 tons: 54°F WBPart-speed fan operation on towers allows the system to be run at the optimal cooling-tower setpoint to minimize the sum of chiller-plus-tower-fan energy.Mark Hydeman, Ken Gillespie, and Ron Kammerud (Pacific Gas & Electric) published a paper in September 1997 showing that the optimal condition for a chiller–tower changes with load and wet bulb. This paper was first presented at the National Cool-Sense Forum in San Francisco.40020060657075808590condenser water setpoint, °F
103 prescriptive HVAC requirements Airside Energy Recovery Required if:Supply air capacity ≥ 5,000 cfmMinimum outdoor air ≥ 70%Recovery system effectiveness ≥ 50%Exceptions (9)Labs, toxic exhaust, etc.Largest exhaust < 75% outdoor airflowHeat recovery with 50% effectiveness is required on the airside when individual fan systems have capacities of 5,000 cfm, of which 70% or more is outdoor air.This effectiveness can be calculated at either heating or cooling design. For cooling design, it must represent total energy transfer—not just sensible. For heating design, effectiveness can be based on dry bulb.There are nine exceptions, including the fact that if there are many small exhaust air ducts, it isn’t cost- effective to recover the heat.
104 energy-recovery technologies Total-Energy Recovery Total-energy, rotary heat exchangers, a.k.a.Enthalpy wheelsHeat wheelsEnergy wheelsDesiccant wheelsMembrane, fixed-plate heat exchangersToday, the most popular total-energy recovery device is a total-energy wheel. The wheel on this slide is installed in an indoor unit.Total-energy rotary wheels go by many different names. They’re also called enthalpy wheels, heat wheels, energy wheels or desiccant wheels.Another total-energy recovery technology uses membrane, fixed-plate heat exchangers. The membrane exchangers are shaped like a fixed-plate exchanger, but they’re made of paper-like material. This material is a membrane that allows moisture to transfer from one airstream to the other.
105 prescriptive HVAC requirements Waterside Energy Recovery Must recover condenser heat for service water heating (SWH) if:Facility operates “24/7” andHeat rejection > 6,000,000 Btu/h andSWH load > 1,000,000 Btu/hWhere required, meet the smaller of:Recover 60% of rejected condenser heat orPreheat water to 85°FCondenser heating is required where there are simultaneous heating and cooling loads. The conditions shown here are often met in hospitals, hotels, correctional facilities, and dormitories.Heat recovery also is likely to become more popular to perform the recovered reheat under the “Simultaneous Heating and Cooling” and “Dehumidification” sections.A chiller with an auxiliary condenser may be an ideal candidate for the required heat recovery.
106 waterside energy recovery Preferential Loading applicationTIPproduction (supply)bypass linedistribution (demand)Proper system design isn’t a requirement in the standard, but it’s a necessity for deriving the maximum benefit from heat-recovery chillers.A preferential loading configuration, shown here, assures that the chiller in the sidestream position receives the warmest entering-water temperature and that it can be fully loaded whenever the system load is high enough. This arrangement is unique because it not only allows preferential loading, but it also permits the chiller (or other cooling device) in the sidestream position to operate at any temperature difference. In other words, it does not need to supply the same temperature water as the other operating chillers. The chiller in this position precools the system return water, reducing the load on the downstream chillers. In this example, a heat-recovery chiller is located in the sidestream position so that it can be preferentially loaded to maximize the amount of heat recovered, thus reducing the overall building energy consumption. Because a heat-recovery chiller is typically less efficient than a standard cooling-only chiller, the heat-recovery chiller need only provide sufficient cooling to meet the heat-recovery load, letting the more efficient cooling-only chillers meet the rest of the cooling load.One drawback of the sidestream arrangement is that it doesn’t add water flow capability to the system; it simply reduces the load on other chillers. Therefore, the other system pumps must ensure that system flow requirements are met. For this reason, the capacity of the sidestream chiller is often smaller than that of the other chillers in the plant.In addition to being useful for energy recovery, preferential loading can also be beneficial in the following applications:In a system that has a high-efficiency chiller along with several standard-efficiency chillers. (The high-efficiency chiller can be preferentially loaded to reduce system energy consumption.)In a system with an alternate-fuel chiller, such as an absorption chiller. (Preferentially loading the alternative-fuel chiller during times of high electricity costs minimizes system energy cost.)heat-recovery chiller in a sidestream piping arrangement
107 prescriptive HVAC requirements Exhaust Hoods Kitchen hoods > 5,000 cfm: Provide makeup air ≥ 50% of exhaust air volumeFume hoods if total capacity > 15,000 cfm:Capability to reduce exhaust and makeup-air volumes to ≤ 50% orDirect makeup-air supply ≥ 75% of exhaust rate at specified conditions orHeat recovery to precondition makeup airKitchen hoods above 5,000 cfm require 50% makeup air that is untreated or only heated to 60°F. Fume hoods must either be capable of part-load operation or use untreated air.
108 prescriptive HVAC requirements Radiant Heating Required for unenclosed spacesException: Loading docks with air curtainsIn outdoor uses, radiant heating is required, with the exception shown.
109 prescriptive HVAC requirements Hot Gas Bypass Limitation Maximum HGBP capacity, % of total capacityRated capacity of system≤ 240,000 Btu/h 50%> 240,000 Btu/h 25%Applied in systems with stepped or continuous unloadingLimitation also pertains to chillersException: Packaged unitary systems ≤ 90,000 Btu/h (7.5 tons)There’s also a limitation on hot gas bypass (NOT hot gas reheat but hot gas BYPASS.) Hot gas bypass is generally used to keep a compressor from cycling … and is very energy IN-efficient. The hot gas bypass limitation applies to systems over 7.5 tons and the limits are noted above. It’s important to understand that this limit also applies to chillers.
110 section 7: Service Water Heating Mandatory provisions:Equipment efficiencyPiping insulationSWH system controls (temperature, pump operation)Pool heaters and coversPrescriptive requirements:Space and water heatingService water heatingThere are requirements for service water heating.
111 ASHRAE Standard 90.1 Section 9: Lighting The lighting section represents a large portion of the energy savings attributable to compliance with the standard.
112 section 9: lighting Scope Lighting controlInterior spacesExterior building features and grounds lightingLighting powerBuilding type and useInterior and exterior lighting levels are specified in the standard, as are controls for lighting.The interior lighting power allowance can be calculated by building area or space function. If the “space function” method is used, lighting power can be traded among spaces as long as the installed interior lighting power doesn’t exceed the interior lighting power allowance.There are exceptions for:emergency lightinglighting required by life safety statutelighting within living units of buildingsdecorative gas lighting
113 existing buildings: Lighting Alterations Replacement lighting systems must meet lighting power density requirementsNew control devices must comply with mandatory provisionsException: Replacing < 50% of luminairesIn existing buildings, the standard applies as shown here.
114 mandatory provisions Interior Lighting Control At least one control in each spaceAutomatic shutoff for buildings > 5,000 ft²Time-of-day scheduleOccupancy sensorSignal from another system to indicate when space is unoccupiedLighting control must be available in each space.Interior lighting controls are required when the building is greater than 5,000 square feet.The automatic lighting shutoff must be automated and based on a schedule, occupancy sensor, or another control system that indicates the area is unoccupied.
115 interior lighting power allowance Building Area Method lighting power allowance (W)= LPD × area (ft²)where LPD = lighting power density (W/ft²)The lighting budget can be done either on a whole-building or on a space-by-space basis.___________________________________[The method for determining the power allowance is given below.]The methodology for determining the Lighting Power Density by space type was jointly developed by the SSPC and the IESNA Energy Management Committee.The methodology provides a set of linked spreadsheets that:Use actual lamp/ballast/luminaire performance data along with professional design decisionsProduce a power allowance that allows appropriate lighting design with the use of efficient technologiesDo not prescribe or encourage a particular type of designAre based on lighting system data and foot-candle LPD calculated for each space typeLPD was further refined based on luminaire lighting characteristics for different room cavity ratios (RCR) to arrive at LPD values for three different RCR ranges: less than 2.5, between 2.5 and 7, and greater than 7. A typical and appropriate RCR was then established for each space type and the associated LPD was selected.
116 building area method for interior Lighting Power Densities Interior LPD, W/ft²Space typeHospitalLibraryManufacturingMuseumOfficeRetailSchoolThis slide and the next compare the 2004 lighting power densities with the 2001 allowances because there have been significant changes.Obviously, these changes will affect the lighting and electrical design. They will also reduce the air conditioning load and steepen the space sensible heat ratio. This may make humidity control more challenging.Make sure you interface with the lighting designer so the HVAC system is not oversized.
117 space-by-space method for interior Lighting Power Densities May trade power between spacesInterior LPD, W/ft²Space typeOffice, enclosedOffice, open planConferenceTrainingLobbyLoungeDiningFood prepNote that using the space by space method does not mean that lighting power needs to be used in a particular space. Simply add all the spaces’ powers up to determine the building lighting power allowance. It may be used in any space you see fit, but the total cannot exceed the allowance.Instead of the Building Area Method, one may use the Space-by-Space Method to add the number of watts by space type and area. Then the larger of the two lighting power allowances (building area or space-by-space) may be used.Again, the lighting levels in the 2004 standard are significantly lower than those in the 2001 standard.
118 space-by-space method Additional Lighting Power May increase interior lighting power allowance for:Decorative luminaires, ≤ 1.0 W/ft² in space where usedLuminaires designed for visual display terminals, ≤ 0.35 W/ft²Retail accent lighting for specific display, ≤ 1.6 W/ft² or 3.9 W/ft² for fine merchandiseAdditional lighting power allowances are shown here.The decorative luminaires might be chandeliers in a hotel ballroomThe 2004 standard clarified that the retail accent lighting allowances only apply to the area of the merchandise being highlighted, not the total retail establishment.
119 Lighting AddendaChangeai: retail display lighting. Gives lighting designers flexibilityIn the lighting area, the retail display lighting requirements were changed to give more flexibility to system designers.As I said, these are just some of the 44 addenda that are included in – but they give you some flavor of the major areas to examine as you move to developing buildings that are 10 percent better than as the prerequisite for LEED 2009.
120 mandatory provisions Exterior Lighting Control Must have some means of automatic shutoff during daylight hoursExterior lighting must be shut off during daylight hours. Many use some type of photosensor to turn them off.
121 mandatory provisions Exterior Lighting Power Lighting-power-density allowances for tradable surfaces, plus additional 5%Tradable exterior surface Maximum LPDParking lots and drives 0.15 W/ft²Building main entries 30 W/lin ft of door widthCanopies 1.25 W/ft²Outdoor sales open areas 0.5 W/ft²Some of the building exterior lighting power limits are shown here. These powers may be traded off between one another, but not interior lighting nor “non-tradable” exterior lighting.May only exchange power among tradable surfaces
122 mandatory provisions Exterior Lighting Power NON-tradable exterior surfacesApplication Maximum LPDBuilding facades 0.2 W/ft² or 5.0 W/lin ftAutomated teller machines 270 W per locationFast-food drive-up windows 400 W per drive-thruParking near 24-hr retail entries 800 W per main entryThere are also exterior lighting power allowances that may not be traded between surfaces or with other exterior lighting. These are in addition to any tradable surfaces lighting power allowance.
123 section 10: other equipment Electric Motors Mandatory provisions:Performance compliant with 1992 Energy Policy ActMinimum nominal full-load efficiencies for general purpose motorsMinimum requirements are spelled out for electric motor efficiency in Section 10 of the standard.
124 Section 11: Energy Cost Budget (ECB) Method ASHRAE Standard 90.1Section 11: Energy Cost Budget (ECB) MethodThe Energy Cost Budget Method is similar to the Canadian Compliance Supplement. In fact, some of the tables for building types and schedules were taken directly from the Canadian supplement.
125 section 11 Energy Cost Budget Method Prescriptive Building Envelope Option (§5.5)general & mandatory provisionsBuilding Envelope Trade-Off Option (§5.6, performance)It’s designed to encourage the design of energy efficient buildings or systems while allowing greater flexibility than the prescriptive paths of the standard.The ECB method can’t be used until the building envelope has been prepared for building permit submittal.It includes mandatory provisions from the Envelope, HVAC, Service Water Heating, Power, Lighting, and Motors and Belts sections of the standard.Adoption authorities can either write their own compliance supplement or adopt the ASHRAE supplement, either in its entirety or portions of it.Energy Cost Budget Method (ECB, §11)proposed building design(new buildings only)90.1-compliant building
126 section 11: Energy Cost Budget Method Used for code or standard complianceSets maximum annual energy cost allowable for proposed designDesign Energy Cost ≤ Energy Cost BudgetECB represents an equivalent 90.1-compliant buildingMust still satisfy mandatory provisionsRemember that using the ECB method compares the energy cost of a base building, as defined by the standard, to the proposed design.Recall, also, that mandatory requirements, such as HVAC equipment efficiency, cannot be traded.Computer simulation aids tradeoffs between building functions
127 section 11: energy cost budget method Simulation Requirements 1,400 hours per yearHourly variations (occupancy, lighting, thermostat setpoints, etc.)Thermal mass effectsTen or more thermal zonesEquipment (part-load performance, capacity and efficiency correction curves)EconomizersBudget building design characteristicsThis slide shows the requirements for simulation programs in ASHRAE Programs that meet these requirements include DOE, EnergyPlus, TRACE, and HAP. Bin analysis programs do not meet these requirements.
128 performance rating method Appendix G Modification of ECB Method (§11)“Provided … to quantify performance that substantially exceeds the requirements of Standard 90.1”Used for Energy & Atmosphere Credit 1 calculation in LEED-NC version 2.2Does NOT offer an alternative compliance path for minimum standard complianceAn addition to the 2004 standard is Appendix G.This is generally used for green building programs, such as the U.S. Green Building Council’s LEED products. In fact, the LEED product for new construction, version 2.2, refers specifically to Appendix G of StandardIt’s important to understand that this appendix does NOT offer a compliance path for minimum standard requirements.
129 appendix G: performance rating method Simulation Requirements 8,760 hours per yearHourly variations (occupancy, lighting, thermostat setpoints, etc.)Thermal mass effectsTen or more thermal zonesEquipment (part-load performance, capacity and efficiency correction curves)EconomizersBudget building design characteristicsAppendix G modeling requirements are different than the ECB method and give more credit for architectural and design decisions that reduce energy consumption and cost in a building.Both the proposed building and a baseline building, as defined by Appendix G, are modeled.
130 Appendix G Changes toImproved identification of baseline buildingsImproved identification of baseline systemsIncreased information for energy modelers
131 using appendix G for LEED-NC’s EA Credit 1 Percent improvement:Both models include all end-use loads (receptacles, process loads, etc.)baseline bldg performanceproposed bldg performance100 ×—Once the models are run, the percent improvement from the baseline is calculated using the equation shown.Both models include receptacle and process loads.
132 EAC1 – Modeling Up to 19 points New BuildingsExisting Building RenovationsPoints12%8%114%10%216%318%420%522%624%726%828%930%1032%1134%1236%1338%1440%1542%1644%1746%1848%19[MICK] Remember that the prerequisite is now 10% less energy cost compared to ASHRAE for new construction and 6% for existing building renovations. In EA credit 1, optimizing energy, we can accrue points.[SLIDE] For new construction, at 12% energy cost reduction you achieve 1 point. For a renovation, 8% reduction allows 1 point to be achieved.Each additional 2% of energy cost savings accrues another credit point.Up to a maximum of 19 points can be achieved. Needless to say, there is significant emphasis on optimizing the energy within the project.Scott will help us examine ways these points can be achieved in a few minutes.
133 ASHRAE Standard 90.1-2007 Who’s Affected? OwnersOccupantsConsulting engineersArchitectsSystem designersInstallersOperatorsThe standard is comprehensive and its impact is extensive—especially in the United States—due to the Energy Policy Act. Everyone connected with building design, construction, or use will be affected by it.ASHRAE and IESNA want to develop a usable standard that conserves energy at a reasonable cost. They accomplish this with input from you.
134 Future of 90.1 90.1-2007 published in late 2007 90.1-2010 Increased attention to energy reduction“A 2010 standard that results in 30% total energy cost savings improvement compared to Standard ” ( Work Plan)Planned for BOD approval in June 2010
135 SSPC 90.1 Accomplishments 06/2007 through 11/17/2009 83 Addenda processed44 finished17 Awaiting BOD approval6 in comment resolution15 began public review 11/6/2009~8 more – web mtgspublicationsUser’s ManualSupplement (1Q-2009) incorporates 20 addenda2010 User’s Manual RFPInterpretations25 official (2 pending)~30 unofficialEISA guidance and appealAppeals2 defended2 on addendum (z) upheldThe numbers do not add to the total addenda processed, since one addendum (ah) failed during the recirculation ballot.
136 90.1 Progress Indicator Information (Some) Energy Saving Addenda in Public Review and not included yetAL – Skylights, Large spacesAM – Fenestration InfiltrationAQ – TPSBB – EnvelopeBF – Continuous Air BarrierBI – Pipe InsulationBN – Fenestration OrientationBS – ReceptaclesBT – Chiller AdjustmentBU – Computer RoomsBX – VAV Heating TemperaturesBY – Lighting Power DensitiesCA – VAV Fan PowerCD – Exterior Lighting controlCE – Multi-level lighting controlAs of Oct 2, 200911.5% savings compared toAssumes same ventilation rate (no savings)Energy Saving Addenda finished, but not included yetE – Airside energy recoveryO – Transformer efficiencyAK – Pump pressure optimizationBG – W2W heat pumpsBH – Supply air temperature resetAA & BP - Lighting controlBQ – Lighting retail allowanceBW – PTACsPortions of others
137 ASHRAE Standard 90.1-2007 Availability Members $88Others $110Read onlineOrder from bookstore (electronic or paper)Check for addenda (continuous maintenance)Download compliance formsThe new standard is published. If you wish to obtain a copy, go to ASHRAE’s online bookstore at It’s available in paper or electronic format. For ASHRAE members the cost is $88; for non-members, it’s $110.We also recommend the 90.1 User’s Manual. It gives a lot of useful information and examples.Also note that the standard may be read online—but it may not be printed.One important fact to remember is that the standard is subject to continuous maintenance. This means that suggested changes can be made to the committee and the committee must consider those changes. As always, changes must be released for public review. What this means is that the standard is now a “living, breathing” document.Members $74Others $93
138 ASHRAE Standard 90.1-2007 Questions? [Answers to commonly asked questions]How do I get more information or training?ASHRAE has short courses (4-hour classes) and developed a two-day Personal Development Series Course on the standard. The United States Department of Energy has hosted two satellite broadcasts on the subject. Videos of the full satellite broadcast are available at:How exactly does 90.1 apply to existing buildings?While this changes by section within the standard, basically, if the component is being changed or updated, it will need to be brought up to the standard’s minimum requirements.Are the updated energy codes being enforced?That varies greatly by jurisdiction. Some locales enforce the energy code very strictly. Others don’t. In July of 2004 ASHRAE sent a letter to the United States Department of Energy suggesting that DOE fund training for code officials to promote enforcement.What’s my local energy code?We’d suggest that you contact your state’s energy code officials. Many of the states have very good web sites. There is also a web site that attempts to track what states are doing with their codes.Can’t I meet the chiller requirements by providing a chiller with a worse full-load efficiency but better IPLV or NPLV?No. Section states “Where multiple rating conditions or performance requirements are provided, the equipment shall satisfy all stated requirements, unless otherwise exempted by footnotes in the table.” Both full-load and part-load requirements MUST be met.Are there exceptions to the requirements discussed in this presentation?Definitely. There is no way that all the exceptions can be covered in a presentation of this length. We suggest you get the standard and the 90.1 User’s Manual to understand the committee’s intent and how the standard is to be applied.Can a design engineer or building owner go beyond the standard? If so, does ASHRAE provide any guidance to do so?Remember that gives minimum requirements. Building and systems can always go beyond these minimum requirements. ASHRAE has a guideline committee, 18P, that is charged with giving guidance as to how to surpass the minimum requirements. The cognizant committee now has a draft, but this guideline has not yet been published.You stated there is a limitation on the percentage of glass allowed. What if the architect wants to go beyond this?There is a specific envelope trade-off option and a program is provided with the 90.1 User’s Manual. By putting in better glass or more insulation, the architect may be able to use more glass.Is a more complete presentation available to Trane’s field sales force?Yes. Along with many other presentations is one that is on the TraneNET siteAlso, you can contact Mick Schwedler (La Crosse Applications Engineering) or Susanna Hanson (La Crosse Chiller Department) if you need more information.