Transcript EnergyPlus Training Part 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
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
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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
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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
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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:

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Occupancy density
Occupancy activity
Lighting
Thermostatic controls
Shading element density
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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
peak
average
reality
how we account
for internal gains
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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)
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ScheduleType
 Used to validate schedule values (optional)
ScheduleType,
Any Number;
ScheduleType,
Fraction,
0.0:1.0,
CONTINUOUS;
ScheduleType,
Temperature,
-60:200,
CONTINUOUS;
ScheduleType,
Control Type,
0:4,
DISCRETE;
!- ScheduleType Name
!- ScheduleType Name
!- range
!- Numeric Type
!- ScheduleType Name
!- range
!- Numeric Type
!- ScheduleType Name
!- range
!- Numeric Type
Notes: Maximum and minimum of range (inclusive) separated by colon
Discrete refers to distinct integer values
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Continuous to any value in the range
DaySchedule
 The day description is
simply a name and the 24
hourly values associated
with that name
 Other forms
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

DaySchedule:Interval
DaySchedule:List
Can handle subhourly
schedule changes
 Hour 1 is Midnight to 1am
DAYSCHEDULE,
OC-1,
Fraction,
0.0,
0.0,
0.0,
0.0,
0.0,
. . .
1.0,
1.0,
0.0,
0.0,
0.0,
0.0,
0.0,
0.0;
!!!!!!!-
Name
ScheduleType
Hour 1
Hour 2
Hour 3
Hour 4
Hour 5
!!!!!!!!-
Hour
Hour
Hour
Hour
Hour
Hour
Hour
Hour
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18
19
20
21
22
23
24
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WeekSchedule
 The week description has an identifier and 12 names
corresponding to previously defined DaySchedules
WEEKSCHEDULE,
ActWeekSchd,
ActDaySchd2,
ActDaySchd1,
ActDaySchd1,
ActDaySchd1,
ActDaySchd1,
ActDaySchd1,
ActDaySchd2,
ActDaySchd3,
ActDaySchd4,
ActDaySchd4,
ActDaySchd3,
ActDaySchd3;
!- Name
!- Sunday DAYSCHEDULE Name
!- Monday DAYSCHEDULE Name
!- Tuesday DAYSCHEDULE Name
!- Wednesday DAYSCHEDULE Name
!- Thursday DAYSCHEDULE Name
!- Friday DAYSCHEDULE Name
!- Saturday DAYSCHEDULE Name
!- Holiday DAYSCHEDULE Name
!- SummerDesignDay DAYSCHEDULE Name
!- WinterDesignDay DAYSCHEDULE Name
!- CustomDay1 DAYSCHEDULE Name
!- CustomDay2 DAYSCHEDULE Name
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Schedule
 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
SCHEDULE,
OCCUPY-1,
Fraction,
OC-WEEK,
1,
1,
12,
31;
!!!!!!!-
Name
ScheduleType
Name of WEEKSCHEDULE 1
Start Month 1
Start Day 1
End Month 1
End Day 1
Repeat
as
needed
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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,
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;
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Types of Internal Gains
People
Lights
Equipment
Infiltration
See “Input Output Reference” –
Space Gains
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Heat Additions from Internal
Gains
 Sensible vs. Latent
 Sensible—energy addition associated with (drybulb) 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)
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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
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People: Example
PEOPLE,
EAST ZONE,
3.000000,
BLDG Sch
1,
0.3000000,
Activity Sch,
EAST ZONE,
ZoneAveraged,
,
Work Eff Sch,
Clothing Sch,
Air Velo Sch,
Fanger;
!!!!!!!!!!!!-
Zone Name
Number of People
Number of People SCHEDULE Name (real--fraction)
Fraction Radiant
Activity level SCHEDULE Name (units W/person)
PEOPLE Group Name
MRT Calculation Type
Surface Name/Angle Factor List Name
Work Efficiency SCHEDULE Name (0.0-1.0,real)
Clothing Insulation SCHEDULE Name (real)
Air Velocity SCHEDULE Name (units m/s, real)
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
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People: Other Notes
 Estimating the Number of People
 Based on type of space/activity
 See ASHRAE Standard 62 for estimates
 Example: 7 people/100m2 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)
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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,
West Wing,
Zone001:Surf001,
0.20,
Zone001:Surf002,
0.20,
Zone001:Surf003,
0.20,
Zone001:Ceiling001,
0.15,
Zone001:Floor001,
0.25;
!!!!!!!!!!!!-
Angle Factor
Zone Name
Surface Name
Angle Factor
Surface Name
Angle Factor
Surface Name
Angle Factor
Surface Name
Angle Factor
Surface Name
Angle Factor
List Name
1
1
2
2
3
3
4
4
5
5
MRT 
Number of Surfaces
 AF T
i 1
i
i
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Lights
Peak Value (all sensible)
Schedule
Radiant, visible, replaceable, return air
fractions (remainder is convection)
Meter end use category
LIGHTS,
EAST ZONE,
BLDG Sch
3,
1464.375,
0.0000000E+00,
0.2000000,
0.2000000,
0.0000000E+00,
GeneralLights;
!!!!!!!!-
Zone Name
SCHEDULE Name
Design Level {W}
Return Air Fraction
Fraction Radiant
Fraction Visible
Fraction Replaceable
LightsEndUseKey
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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/ft2, example:
1.3 W/ft2 for office setting
 ASHRAE Standard 90.1
 ASHRAE Handbook of Fundamentals,
Nonresidential Cooling and Heating Load
Calculation Procedures Chapter
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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,
Basically, energy that does
not affect the zone heat
balance (vented to exterior
environment)
NORTH ZONE,
BLDG Sch 2,
2928.751,
0.0,
0.3,
0.0;
!!!!!!-
Zone Name
SCHEDULE Name
Design Level {W}
Fraction Latent
Fraction Radiant
Fraction Lost
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Electric Equipment: Other Notes
 Estimating the Input for Design Level
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
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/m2 but actual consumption might only be
8W/m2 in an office setting)
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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
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Steam Equipment

Other Equipment
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“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:
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BASEBOARD HEATER:Water:Convective
BASEBOARD HEATER:Electric:Convective
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Baseboard Heat Example
Example of Baseboard Heat usage:
BASEBOARD HEAT,
North Zone , !- Zone Name
Baseboard Availability Schedule , !- SCHEDULE Name
15000,
!- Capacity at low temperature in W (> 0)
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!- 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)
Response:
Baseboard Output (W)
15000
10000
5000
0
30
40
50
60
70
Outside Dry-Bulb
Temperature
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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,
Outside Lighting,
ExtLightingSched,
200.0;
!!!!-
only used for reporting, does not affect loads
Descriptive Name
SCHEDULE Name
Design Level (Watts)
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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
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Infiltration (cont’d)
What it’s not:
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
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)
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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
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Accounting for Infiltration
Heat Gain/Loss
Difficult to estimate
More sophisticated estimates generally
n
take a form similar to: Q=c(Dp)
Estimation based on either ACH or
“crack” method

See ASHRAE Handbook of Fundamentals,
Ventilation and Infiltration Chapter for
more details
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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
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Infiltration in EnergyPlus
Example from an IDF file:
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)
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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
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