1. Lecture 8: Schedules and Internal Heat Gains Material prepared by GARD Analytics, Inc. and University of Illinois at Urbana-Champaign under contract to the National Renewable Energy Laboratory. All material Copyright 2002-2003 U.S.D.O.E. - All rights reserved

2. 2 Importance of this Lecture to the Simulation of Buildings  Every building is different in many ways: Location/exterior environment Construction/building envelope Space usage/interior environment HVAC system  Thermal simulation requires information about the functions taking place inside the building and how these might add or subtract heat from the zones  Thermal simulation requires information on air leakage to and from the building to determine its effect on the building heating and cooling needs  Nothing is constant inside a building—people come and go, lights and equipment gets turned on and off, etc.—and the thermal simulation needs details on what is happening through the day and year within a building

3. 3 Purpose of this Lecture  Gain an understanding of how to internal heat gains impact and space and how to specify them People, Lights, Equipment, etc. Infiltration Schedules

4. 4 Keywords Covered in this Lecture  ScheduleType  DaySchedule  WeekSchedule  Schedule  People and AngleFactorList  Lights  Equipment—Electric, Gas, Hot Water, Steam, Baseboard (scheduled), Other  Exterior Equipment  Infiltration

5. 5 Schedules  In general, schedules are a way of specifying how much or many of a particular quantity is present or at what level something should be set, including: Occupancy density Occupancy activity Lighting Thermostatic controls Shading element density

6. 6 Schedules (cont’d)  For internal gains, schedules allow us to come a little closer to the real variation of building quantities than single values % of peak occupancy reality how we account for internal gains average peak

7. 7 Schedules in EnergyPlus  EnergyPlus uses a hierarchy of schedule pieces to create unique schedules  DaySchedule: 24 hour period of schedule values  WeekSchedule: Consists of various DaySchedule definitions for an entire week  Schedule: Consists of various WeekSchedule definitions for an entire year  ScheduleType: Optional feature that allows for some validation and limitation of schedules (avoid mistakes)

8. 8 ScheduleType ScheduleType, Any Number; !- ScheduleType Name ScheduleType, Fraction, !- ScheduleType Name 0.0:1.0, !- range CONTINUOUS; !- Numeric Type ScheduleType, Temperature, !- ScheduleType Name -60:200, !- range CONTINUOUS; !- Numeric Type ScheduleType, Control Type, !- ScheduleType Name 0:4, !- range DISCRETE; !- Numeric Type  Used to validate schedule values (optional) Notes:Maximum and minimum of range (inclusive) separated by colon Discrete refers to distinct integer values Continuous to any value in the range

9. 9 DaySchedule DAYSCHEDULE, OC-1, !- Name Fraction, !- ScheduleType 0.0, !- Hour 1 0.0, !- Hour 2 0.0, !- Hour 3 0.0, !- Hour 4 0.0, !- Hour 5... 1.0, !- Hour 17 1.0, !- Hour 18 0.0, !- Hour 19 0.0, !- Hour 20 0.0, !- Hour 21 0.0, !- Hour 22 0.0, !- Hour 23 0.0; !- Hour 24  The day description is simply a name and the 24 hourly values associated with that name  Other forms DaySchedule:Interval DaySchedule:List Can handle subhourly schedule changes  Hour 1 is Midnight to 1am

10. 10 WeekSchedule WEEKSCHEDULE, ActWeekSchd, !- Name ActDaySchd2, !- Sunday DAYSCHEDULE Name ActDaySchd1, !- Monday DAYSCHEDULE Name ActDaySchd1, !- Tuesday DAYSCHEDULE Name ActDaySchd1, !- Wednesday DAYSCHEDULE Name ActDaySchd1, !- Thursday DAYSCHEDULE Name ActDaySchd1, !- Friday DAYSCHEDULE Name ActDaySchd2, !- Saturday DAYSCHEDULE Name ActDaySchd3, !- Holiday DAYSCHEDULE Name ActDaySchd4, !- SummerDesignDay DAYSCHEDULE Name ActDaySchd4, !- WinterDesignDay DAYSCHEDULE Name ActDaySchd3, !- CustomDay1 DAYSCHEDULE Name ActDaySchd3; !- CustomDay2 DAYSCHEDULE Name  The week description has an identifier and 12 names corresponding to previously defined DaySchedules

11. 11 Schedule SCHEDULE, OCCUPY-1, !- Name Fraction, !- ScheduleType OC-WEEK, !- Name of WEEKSCHEDULE 1 1, !- Start Month 1 1, !- Start Day 1 12, !- End Month 1 31; !- End Day 1  Annual schedule contains an identifier and the names and from-thru dates of the week schedules associated with the annual schedule  Up to 52 week schedules can be specified, allowing unique specification of every day of the year  Other forms WeekSchedule:Compact Schedule:Compact Repeat as needed

12. 12 Complete Schedule Specification  Example of an EnergyPlus Schedule: ScheduleType, Any Number; DaySchedule, Weekday, Any Number, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.10, 0.50, 1.00, 1.00, 1.00, 1.00, 0.50, 1.00, 1.00, 1.00, 0.50, 0.10, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00; DaySchedule, Weekend, Any Number, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00; WeekSchedule, Office Occupancy Schedule, Weekend, Weekday, Weekday, Weekday, Weekday, Weekday, Weekend, Weekend, Weekend, Weekend, Weekend, Weekend; Schedule, Office Occupancy Schedule, 1, 1, 12, 31;

13. 13 Types of Internal Gains  People  Lights  Equipment  Infiltration  See “Input Output Reference” – Space Gains

14. 14 Heat Additions from Internal Gains  Sensible vs. Latent Sensible—energy addition associated with (dry- bulb) temperature change in zone Latent—energy addition associate with moisture/humidity change in zone  Sensible Heat Gains Convection Thermal (Long Wavelength) Radiation Visible (Short Wavelength) Radiation (generally lights only)

15. 15 People  Peak Value  Schedule  Radiant fraction (remainder of sensible gain is convection)  Activity level schedule (W/person) Total heat gain—broken up into sensible and latent fractions within the program automatically  Thermal comfort reports Fanger Pierce Two-Node Kansas State University Two-Node

16. 16 People: Example PEOPLE, EAST ZONE, !- Zone Name 3.000000, !- Number of People BLDG Sch 1, !- Number of People SCHEDULE Name (real--fraction) 0.3000000, !- Fraction Radiant Activity Sch, !- Activity level SCHEDULE Name (units W/person) EAST ZONE, !- PEOPLE Group Name ZoneAveraged, !- MRT Calculation Type, !- Surface Name/Angle Factor List Name Work Eff Sch, !- Work Efficiency SCHEDULE Name (0.0-1.0,real) Clothing Sch, !- Clothing Insulation SCHEDULE Name (real) Air Velo Sch, !- Air Velocity SCHEDULE Name (units m/s, real) Fanger; !- Thermal Comfort Report Type (Fanger, Pierce, KSU) Options are ZoneAveraged, SurfaceWeighted, or AngleFactor; determines the position that MRT is calculated at (center of zone, near a surface, or at a particular point through user supplied angle factors) Apply only to thermal comfort models, not the heat balance

17. 17 People: Other Notes  Estimating the Number of People Based on type of space/activity See ASHRAE Standard 62 for estimates Example: 7 people/100m 2 for an office setting  Estimating the Activity Level Based on activity within the zone See ASHRAE Handbook of Fundamentals, Thermal Comfort Chapter or Nonresidential Cooling and Heating Load Calculation Procedures Chapter for estimates Example: 115W/person for seated, light office work  Estimating the Percent Radiant Common values range from 30-40% (0.3-0.4)

18. 18 AngleFactorList  Allows user to specify angle factors for various surfaces to define influence on Mean Radiant Temperature (MRT) for thermal comfort evaluation AngleFactorList, West Wing Angle Factors, !- Angle Factor List Name West Wing, !- Zone Name Zone001:Surf001, !- Surface Name 1 0.20, !- Angle Factor 1 Zone001:Surf002, !- Surface Name 2 0.20, !- Angle Factor 2 Zone001:Surf003, !- Surface Name 3 0.20, !- Angle Factor 3 Zone001:Ceiling001, !- Surface Name 4 0.15, !- Angle Factor 4 Zone001:Floor001, !- Surface Name 5 0.25; !- Angle Factor 5

19. 19 Lights  Peak Value (all sensible)  Schedule  Radiant, visible, replaceable, return air fractions (remainder is convection)  Meter end use category LIGHTS, EAST ZONE, !- Zone Name BLDG Sch 3, !- SCHEDULE Name 1464.375, !- Design Level {W} 0.0000000E+00, !- Return Air Fraction 0.2000000, !- Fraction Radiant 0.2000000, !- Fraction Visible 0.0000000E+00, !- Fraction Replaceable GeneralLights; !- LightsEndUseKey

20. 20 Lights: Other Notes  Estimating the Input for Lighting Level Count the number and wattage of bulbs in zone Estimate using information from:  Typically ranges from 1.0 – 2.0 W/ft 2, example: 1.3 W/ft 2 for office setting  ASHRAE Standard 90.1  ASHRAE Handbook of Fundamentals, Nonresidential Cooling and Heating Load Calculation Procedures Chapter

21. 21 Electric Equipment  Peak Value  Schedule  Latent fraction is fraction of total  Radiant and lost fractions of sensible only (remainder of sensible is convection) ELECTRIC EQUIPMENT, NORTH ZONE, !- Zone Name BLDG Sch 2, !- SCHEDULE Name 2928.751, !- Design Level {W} 0.0, !- Fraction Latent 0.3, !- Fraction Radiant 0.0; !- Fraction Lost Basically, energy that does not affect the zone heat balance (vented to exterior environment)

22. 22 Electric Equipment: Other Notes  Estimating the Input for Design Level See ASHRAE Handbook of Fundamentals, Nonresidential Cooling and Heating Load Calculation Procedures Chapter for approximate levels for individual components Note: Nameplate ratings are generally not good estimates of power consumption of electrical equipment (example—nameplates might add up to 35 W/m 2 but actual consumption might only be 8W/m 2 in an office setting)

23. 23 Other Types of Equipment  Other equipment types in EnergyPlus that have same input format as Electric Equipment (just a different keyword) Gas Equipment Hot Water Equipment Steam Equipment Other Equipment

24. 24 “Scheduled” Baseboard Heaters  Moderately controllable baseboard heaters that do not interact with the rest of the HVAC system  Keyword is “Baseboard Heat”  Baseboard Heat is first priority and will react based on outside dry-bulb temperature and input definition  Baseboard that interacts with the HVAC system and controlled based on zone temperature under the following keywords: BASEBOARD HEATER:Water:Convective BASEBOARD HEATER:Electric:Convective

25. 25 Baseboard Heat Example  Example of Baseboard Heat usage:  Response: BASEBOARD HEAT, North Zone, !- Zone Name Baseboard Availability Schedule, !- SCHEDULE Name 15000, !- Capacity at low temperature in W (> 0) 32, !- Low Temperature in degrees C 0, !- Capacity at high temperature in W (>= 0) 65, !- High Temperature in degrees C 0.3; !- Fraction Radiant (remainder of heat is convective) Outside Dry-Bulb Temperature Baseboard Output (W) 0 5000 10000 15000 3040506070

26. 26 Exterior Equipment  Convenient way to account for elements on exterior of building that add to overall energy consumption of site but do not affect heat balance of any zones ExteriorLights ExteriorFuelEquipment  ExteriorWaterEquipment ExteriorLights, !- only used for reporting, does not affect loads Outside Lighting, !- Descriptive Name ExtLightingSched, !- SCHEDULE Name 200.0; !- Design Level (Watts)

27. 27 Infiltration  What is it? Definition: uncontrolled or unintended flow of outdoor air into a building due to…  Cracks and other unintentional openings  Normal use of exterior doors  Through building materials

28. 28 Infiltration (cont’d)  What it’s not: Exfiltration: uncontrolled flow of indoor air out of the building, caused by “pressurizing” the building through a mechanical system (no effect on zone heat balance but effect on HVAC system) Ventilation: purposeful opening of windows or doors to promote air exchange with the outside environment (see future lecture)

29. 29 Infiltration: Causes  Cause: pressure differential Flow of mass from higher pressure to lower pressure area  Driving forces: Wind Buoyancy or “stack” effect HVAC system Note: all of these can vary based on location within a building

30. 30 Accounting for Infiltration Heat Gain/Loss  Difficult to estimate  More sophisticated estimates generally take a form similar to: Q=c(  p) n  Estimation based on either ACH or “crack” method See ASHRAE Handbook of Fundamentals, Ventilation and Infiltration Chapter for more details

31. 31 ACH: Air Changes per Hour  Definition: fraction of room air volume exchanged with outside air in a given hour  An ACH of 1.0 means that the entire air volume of a space is replaced with outside air each hour Heat gain/loss can be significant Effect moderated by energy storage within the building

32. 32 Infiltration in EnergyPlus INFILTRATION, !- Infiltration is specified as a design level which is modified !- by a schedule fraction, temperature difference and wind speed: !- Infiltration = Idesign * Fschedule * !- (A + B*|Tzone-Todb| + C*WindSpd + D * WindSpd**2) West Wing, !- Zone Name CONSTANT, !- SCHEDULE Name (Fschedule in Equation) 0.12, !- Design Volume Flow Rate in m3/s (Idesign in Equation) 1.0, !- Constant Term Coefficient (“A” in Equation) 0.0, !- Temperature Term Coefficient (“B” in Equation) 0.0, !- Velocity Term Coefficient (“C” in Equation) 0.0; !- Velocity Squared Term Coefficient (“D” in Equation)  Example from an IDF file:

33. 33 Summary  Schedules are a vital part of EnergyPlus input and play a role in the definition of many different components  Schedules are a hierarchy of: Day schedules Week schedules Schedules  Scheduled heat gains/losses such as People, Lights, Equipment, Infiltration, etc. can have a significant impact on conditions within a zone and must be taken into account