Energy Management Opportunities in Heating, Ventilation and Air Conditioning (HVAC)

Your panelists Benefits, Technologies & Services: Mike Carter and Mark Farrell, Energy Engineers

Productivity Comfort Expense Why is HVAC important? Source: www.doe.gov Source: www.bcs.org

Contents Basics Cooling Chillers Packaged Rooftops Packaged Terminal Air Conditioners (PTACs) Geothermal Heat Pumps Heating Electric/Electrode Boilers Space Heaters Accessories Energy-Savings Tips Business Solutions Toolkit Rebates/Incentives Source: NREL

HVAC basics Power versus Energy Kilowatt (kW), or demand, is a measure of power, similar to the speedometer of your car that records the rate at which miles are traveled. A bigger engine is required to travel at a faster rate. Kilowatt-hour (kWh) is a measure of energy consumption, similar to the odometer on your car which measures the miles traveled. Energy cost = energy consumption x unit cost = kWh x $/kWh = kW x hrs x $/kWh A 50-ton chiller with a 0.8 kW/ton efficiency costs about $11,200 annually when operating 2,800 load hours (40 kW x 2,800 hr x $0.10/kWh national average) Source: stock.xchng Source: Commonwealth of Kentucky

Dry Bulb Temperature (°F) Wet Bulb Temperature (°F) HVAC basics Temperature Dry bulb Normal thermometer Wet bulb Bulb wrapped in cloth—called a sock—that is kept wet with water via wicking. Dew point Temperature to which air must be cooled for the water vapor component to reach saturation and condense into water. Source: Microsoft Encarta Dry Bulb Temperature (°F) Relative Humidity Wet Bulb Temperature (°F) Dew Point (°F) 70 100% 60% 61 56 30% 53 38 55 48 42 40% 45 37 Not Sustainable Ice

HVAC basics Relative Humidity Relative humidity compares water vapor in the air with the concentration of water vapor that the atmosphere could hold (if the atmosphere were at saturation). Usually expressed as a percentage. When the actual concentration of water vapor in air is equal to the water vapor concentration at saturation, the relative humidity is 100%. There is one gallon of water in a 20' x 50' x 8' room at 68ºF and 100% RH There is only 0.1 teaspoon of water per cubic foot of air at 68ºF and 100% RH Operation at 78°F / 40% RH provides the same level of occupant comfort as 74°F / 50% RH does due to evaporative cooling. 4C 40F 100% Relative Humidity H2O In this example, specific (absolute) humidity does not change until the dew point is reached.

HVAC basics Degree Days Degree day calculations provide a rough estimate of the heating and cooling load for a particular location. Degree days are based on the difference between a day's average daily temperature and the "balance point" temperature of 65°F (or 18°C). Cooling Degree Day (CDD) = (Average Temperature – 65°F) x days/month Heating Degree Days (HDD) = (65°F – Average Temperature) x days/month Location dependent and data available from National Climate Data Center (NCDC), WeatherUnderground, and other sources. Source: Utility Allowance

HVAC basics Load Hours HVAC load hours may be calculated from degree days using a formula which incorporates Outside Design Temperatures. Cooling Load Hours (CLH) = CDD x 24 / (Cooling Outside Design Temperature – 65°F) Cooling Outside Design Temperature (ODT) is in the range of 70°F to 105°F Heating Load Hours (HLH) = HDD x 24 / (65°F – Heating Outside Design Temperature) Heating Outside Design Temperature (ODT) is typically between -12°F and 40°F. It is necessary to reduce the heating load hours by about 40% to match actual energy consumption.

HVAC basics HVAC Load Hours Source: Louisiana Department of Natural Resources, Technology Assessment Division

HVAC basics Efficiency Ratings One ton (12,000 Btu/hr) equals 3.516 kW at 100% efficiency Coefficient of Performance (COP) COP = Rated Cooling Output, kBtuh / Rated electrical input, kBtuh Full Load Value (FLV) FLV = kW/ton COP = 3.516 (kW/ton) / FLV efficiency rating (kW/ton) Energy Efficiency Ratio (EER) EER = Cooling output (Btu) / Electricity consumed (watt) EER = 12,000 Btu per ton / FLV (watt per ton) EER = COP x 3.413 Application Part Load Value (APLV) Other than full load Integrated Part Load Value (IPLV) Weighted average of full load and part load FLV (kW/ton) COP EER 0.6 5.9 20 0.75 4.7 16 1.0 3.5 12 1.5 2.3 8

Seasonal Energy Efficiency Ratio (SEER) HVAC basics Seasonal Energy Efficiency Ratio (SEER) Test conditions for determining SEER values are defined by ANSI/ARI standard 210-240-2008. Indoor air across the evaporator at 80ºF with 50% RH (wet) and <20% RH (dry) Outdoor air across condenser at 82ºF with 40% RH (wet) Outdoor air at 95ºF and 40% RH (Test A) is used to establish capacity and EER Four categories of air-conditioning systems are tested. ARI does not require manufacturers to report the results of dehumidification performance. SEER = (1 - (0.5 x [1 - (EERC/EERD))/(1 - CLF)]) x EERB EERB = Energy Efficiency Ratio determined from Test B (steady, wet) EERC = Energy Efficiency Ratio determined from Test C (steady, dry) EERD = Energy Efficiency Ratio determined from Test D (cyclic, dry) CLF = Cooling Load Factor

Estimation of annual operating cost HVAC basics Estimation of annual operating cost 300 ton chiller; FLV = 0.75 kW/ton (EER=16, COP=4.7); $0.10/kWh; national average Energy cost = Size (ton) x FLV (kW/ton) x CLH (hrs) x Electric rate ($/kWh) Energy cost = 300 ton x 0.75 kW/ton x 600 hrs x $0.10/kWh = $13,500 5 ton heat pump; 13 SEER Energy cost = [Size (MBtuh) x CLH (hrs)]/ SEER (Btu/watt) x Electric rate ($/kWh) Energy cost = [5 ton x 12 Mbtuh/ton x 600 hrs]/ 13 Btu/w x $0.10/kWh = $275

HVAC basics Vapor Compression/Expansion Cycle Source: www.makinemekanik.com

HVAC basics Refrigerants Issues are depletion of the ozone layer and contribution to global warming Manufacturers still are allowed to produce R-22 to service existing equipment After 2020, cannot produce R-22, but can service existing systems Refrigerant ODP1 GWP2 Application CFC-11 1.0 4,680 Centrifugal chillers CFC-12 10,720 Chillers, refrigerators HCFC-22 0.04 1,780 AC, chillers HCFC-123 0.02 76 R-11 replacement HFC-134a <0.00001 1,320 R-12 or R-22 replacement HFC-407c 1,700 R-22 replacement HFC-410a 1,890 AC 1Ozone Depletion Potential 2Global Warming Potential

HVAC basics Delivery Water is much denser and stores much more heat [cooling]. A 1" (25 mm) diameter pipe containing hot/cold water can deliver more energy than a 18" x 12" (0.45 m x 0.3 m) duct, even though the air is moving much faster in the duct than the water in the pipe.

HVAC basics Indoor Air Quality ASHRAE 62.1-2007 Ventilation for Acceptable Indoor Air Quality “Air in which there are no known contaminants at harmful concentrations as determined by cognizant authorities and with which a substantial majority (80% or more) of the people exposed do not express dissatisfaction.” Ventilation Rate Procedure People Outdoor Air Rate (Rp) Area Outdoor Air Rate (Ra) For instance, office areas—5 cfm/person and 0.06 cfm/ft² Indoor Air Quality (IAQ) Procedure Based on an analysis of contaminant sources, contaminant concentration targets, and perceived acceptability targets. CO2 sensors are one method Credit is given for controls that remove contaminants, such as filters and UV light, that can achieve concentrations equal to or lower than those achieved by the Ventilation Rate Procedure.

Cooling Source: EERE Chillers Source: ORNL Centrifugal Chiller Chiller Minimum Efficiency Requirements (ASHRAE 90.1-2004) Compressor Type/Capacity Full-Load Rating, COP (kBtu) Full-Load Rating, FLV (kW/ton) Part-Load Ratings, IPLV (kBtu) Reciprocating (30-150 tons) 4.20 0.84 5.05 Screw/Scroll (<150 tons) 4.45 0.80 5.20 Screw (150-300 tons) 4.90 0.72 5.60 Screw (301-800 tons) 5.50 0.64 6.15 Centrifugal (<150 tons) 5.00 0.70 5.25 Best available Full-Load FLV is 0.47-0.58 kW/ton for large (>150 ton) water-cooled chillers

Cooling Water-cooled centrifugal chiller versus air-cooled screw chiller (20-year life) in office building Energy simulation using DOE-2.2 Calculation Core Engine Net Present Value (NPV) of total costs of ownership Cost Category 100-ton 500-ton Air Water New York City Initial 50% 68% 22% 42% Energy 40% 20% 63% 45% Maintenance 10% 12% 15% 13% Minneapolis 72% 78% 60% 16% 35% Source: Total Cost of Ownership For Air-Cooled and Water-Cooled Chiller Systems, Ramez Naguib

Chiller Maintenance Tips Cooling Chiller Maintenance Tips Visual check of compressor oil (darker is worse). Change oil on large systems once a year and clean particles from case. Take superheat and subcooling temperature readings to obtain chiller's maximum efficiency. Install water gauges so you can see pressure drops, particularly through the evaporator. If tubes need cleaning and the interiors of the tubes are smooth bore, technicians can remove the sludge with bristle brushes attached to long metal rods. Put a bypass valve on the end of the pipe run going to the chillers to get the proper water flow (overflow can cause vibration, damaging the copper tubes). Clean water tower condensers and unclog spray nozzles, especially in the spring. Check for high vibration on a capillary line (causes leaks) and secure all vibrating lines. Source: John C. Schaub Inc., Mt. Laurel, NJ

Full-load EER (Btu/watt) Cooling / heating Packaged Rooftop Image courtesy of McQuay International Unitary Air Conditioner Minimum Efficiency Requirements ASHRAE 90.1-2004 Full-load EER (Btu/watt) Size Range Pre-2010 As of 2010* 65-135 kBtu/hr (5-11 ton) 10.3 11.2 135-240 kBtu/hr (11-20 ton) 9.7 11.0 240-760 kBtu/hr (20-63 ton) 9.5 10.0 >760 kBtu/hr (>63 ton) 9.2 *Phase-out date for R-22 refrigerant

Packaged Terminal Air Conditioners (PTACs) Cooling / heating Packaged Terminal Air Conditioners (PTACs) EER of 10 to 12 available today Suppliers include Amana, Bard, Carrier, ClimateMaster, Friedrich, GE, and Skymark PTAC/PTHP Minimum Efficiency Requirements ASHRAE 90.1-2001 Replacement New Construction Cooling Full-load EER (Btu/watt) PTAC (7,000 Btuh) 9.4 11.0 PTAC (15,000 Btuh) 7.7 9.3 PTHP (7,000 Btuh) 10.8 PTHP (15,000 Btuh) 7.6 9.1 Heating Full-load COP (Kbtuh) 2.7 3.0 2.5 2.8 Source: www.amana-ptac.com/

Geothermal or Water-Source Heat Pump Cooling / heating Geothermal or Water-Source Heat Pump Takes advantage of underground temperatures that range from 45°F (7°C) to 75°F (21°C). Roughly 30% savings compared to AC/Boiler or AC/Furnace combination Geothermal requires higher capital investment and requires a significant amount of space Hybrid geothermal saves on first cost but operating costs are higher Image courtesy of ECS Geothermal Loop Depth Length/ton Vertical 100-500' 300-400'/ton Horizontal 5-6' 800'/ton Pond >8' 400'/ton

Cooling / heating Coil Cleaning Most commercial HVAC units have multiple coils stacked or sandwiched together. Outdoor condenser coils lose less performance with blockage than indoor evaporator coils. If the evaporator airflow of a 3-ton rooftop unit is restricted by 36%, the capacity drop is 19.4%. This changes the 3-ton unit to a 2.5-ton unit. On the other hand, when the condenser coils are 56% restricted, the capacity drops only 10.9%. Blocked condenser coils can increase condensing temperature by 8°F to 10°F resulting in a 6% to 8% increase in power consumption. You can check coil performance by measuring the air temperature drop across the coils. Larger temperature drops of 30ºF or higher indicate that a coil cleaning is in order. You can also measure supply-fan amperage or filter/coil pressure drop (with fresh filters) and compare this data against last year's readings. Image courtesy of Coil-Tech

Heating Electric Boilers Electrode Steam Boilers Available from 10 kW for the smaller units up to over 3,000 kW Often used in tandem with a gas-fired boiler in a fuel-switching strategy Replacement of an electric element bundle (13-18 year life) can range in price from $2,000 to $2,500 for a 75 kW to 100 kW electric boiler Electrode Steam Boilers Operate at high voltages (12 kV or 24 kV) Submersible electrode boilers Rely on immersed electrodes to conduct electricity through the boiler water High-velocity jet electrode boilers In this design, the water jet (striking an electrode plate) is the resistance element Pros include lower installed capital cost, higher reliability, higher efficiency (99.5% at 100% output) and rapid response Source: Precision Boilers

Heating Space Heaters All portable electric heaters using a heating element are equally efficient in that they essentially convert all the electricity they use into heat Only more cost-effective than whole-house furnaces if temperature is reduced in other rooms Quartz "Infrared" space heaters such as SunHeat and EdenPure Infrared radiation does not warm you directly Traditional infrared (picture) has the coils and lamps exposed for direct line of site radiation Ceramic and oil-filled heaters arguably provide greater heating comfort because they retain some heat after the current is off Source: Fostoria Industries

Economizers bring in cool outside air Accessories Economizers bring in cool outside air Typical 2 to 5 year payback for economizers Required by ASHRAE 90 for >5 tons in cool/dry climates (West) and >11 tons in cool/moist climates (Midwest), but not in warm/moist climates (Southeast) Four Economizer Modes Mode Temp. (ºF) Mechanical Damper Heating <30 On Closed Modulated Economizer 30-55 Off Varies Integrated Economizer 55-75 Open Cooling >75

Heat Recovery Ventilators Accessories Heat Recovery Ventilators Can recover about 60% to 70% of heat in exiting air Low grade heat for space heating and equipment expense results in long paybacks A solution to ASHRAE 62 IAQ requirements Source: George Retseck Illustrations

Energy/Enthalpy/Desiccant Wheels Accessories Energy/Enthalpy/Desiccant Wheels Can recover about 70% to 80% of the energy in the exiting air and deliver that energy to the incoming air. Desiccant wheels are most cost effective in climates with extreme winters or summers, and where fuel costs are high. In mild climates, the cost of the additional electricity consumed by the system fans and drum motor may exceed the energy savings from not having to condition the supply air. Source: Fläkt Woods Source: EERE

Thermal Energy Storage (TES) Accessories Thermal Energy Storage (TES) Thermal energy storage makes ice or chilled water during the night—shifts peak. Full Storage system shifts the entire load to off-peak hours and is driven by electric rates and rebates. In a Partial Storage system, a much smaller chiller runs during both peak and off-peak hours with help from stored cooling during peak hours. Attractive when more cooling capacity is needed or when a chiller needs to be replaced. Ice Energy (Windsor, CO) offers factory assembled modular ice making systems (Ice Bear) for small to medium-sized commercial applications. Image courtesy of CALMAC Manufacturing Corporation

Thermal Energy Storage (TES) Accessories Thermal Energy Storage (TES) Ice can absorb eight times the thermal energy of chilled water. Three up-front decisions during system design: How the ice is made and stored (ice on coil—internal melt, ice on coil—external melt, or encapsulated ice). How the ice bank is discharged. How cold is transported to the load (slurry systems versus brine or glycol transfer). Image courtesy of FAFCO, Incorporated

Accessories Thermal Energy Storage (TES) Example: Shifting from peak to non-peak times with a resultant 600 kW drop in peak demand (1,500 kW to 900 kW) For example– at a demand charge of $8.00/kW, that saves $4,800 per month. Additional savings are possible if time-of-use rates result in a lower $/kWh energy charge during off-peak hours. Example: A normally 400-ton chiller outputting 3,000 ton-hours per day might be replaced by a 160-ton chiller. Produces 1,600 ton-hours during a 10-hour peak time period. Produces 1,400 ton-hours during a 14-hour off-peak period.

Energy-savings tips Temperature Setback/Setforward Save 3% per °F per 24 hr 72°F  68°F ( 4°F) for 12 hr saves 6% Obtain Proper Humidity Control In the summer, decrease relative humidity (RH) to feel cool. Operation at 78°F / 40% RH provides the same level of occupant comfort as 74°F / 50% RH does. 74°F  78°F setforward for 24 hr saves 10% to 12% Remove moisture with desiccant or enthalpy/heat wheel Relative humidity >70% with temperature > 70°F can encourage mold growth! In the winter, opposite applies—raise RH to feel warm. Add moisture with evaporative humidifier Ultrasonic humidifiers require filtered water

Energy-savings tips Narrow your chiller water temperature set points Typical conditions are chilled water temperature of 42°F and condensing water temperature of 80°F to 85°F. 2% savings per °F that chilled water temperature is raised 5°F to 10°F increase is possible; more may cause damage and reduce cooling capacity (ton rating) Efficiency benefits from lowering condensing water temperature are offset by increased fan and pump operation, along with reduced cooling capacity. Variable Frequency Drives (VFDs) and oversizing the cooling tower can help The larger the system, the greater the net energy savings

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Rocky Mountain Power FinAnswer Express FinAnswer Express is for commercial and industrial customers– either retrofit or new construction Pre-calculated incentives for HVAC equipment and high-efficiency lighting Custom incentives may be available for other types of equipment Incentive process (pre-purchase agreement or post purchase application) varies by technology and project type Please understand the process before you purchase! Check our website for on-line forms plus trade allies available to help Also check for state and federal tax incentives at dsire.org

RMP Energy FinAnswer Applies to comprehensive commercial or industrial projects– either new construction or commercial retrofit* Lighting and non-lighting projects can be packaged Starts with an energy analysis to identify options and highest priority measures Commissioning is required for most measures Incentives are project-based Payable by one-time lump sum check, per project Incentive agreement must be signed before equipment is purchased Check our website for participation steps and online forms *Commercial retrofit projects must be at least 20,000 sq. ft. to be eligible

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