Transcript PIER Research for the 2008 Residential Building Standards

2013 RESIDENTIAL COMPLIANCE
SOFTWARE PROJECT
Program Advisory Committee (PAC) Meeting
July 17, 2012
Bruce Wilcox, P. E.
Berkeley CA
[email protected]
2013 RESIDENTIAL SOFTWARE
COMPLIANCE PROJECT GOALS



Provide public software for 2013
Standards compliance
Improve accuracy, particularly in
cooling, to support zero net energy
goals
Foster collaborative software
environment for the future
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Project Technical Team

Bruce Wilcox
Prime Contractor, Project Manager, Technical Lead

Chip Barnaby
CSE Lead Programmer

Scott Criswell
Compliance Manager Lead Programmer

Dave Krinkel
Development Plan

Phil Niles
CSE chief scientist

Robert Scott
Compliance Form Generator

Ken Nittler
Compliance Ruleset

Marc Hoeschele
DHW Simulation

Doug Herr
DHW Programmer

John Proctor
HVAC modeling
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Compliance Data
Registry
Compliance Data
Repository
Compliance User
3rd Party Tool
3rd Party Tool
Building Energy Code
Compliance (CBECC)
Compliance Report
Generator
Compliance Manager Software
CSE Simulation Engine
HERS Ruleset
2013 Title-24 Compliance
Ruleset
& TDV
DHW Engine
2013 Title-24
weather data
Diagram key:
Transfer of building model
(multiple arrows imply transfer of multiple building models)
Transfer of compliance reports
Inter-process communication of data and/or API calls
Pale Blocks
Possible future modules
Current Project Schedule
Compliance Manager Software
CSE upgrades
New Construction Rules
New Construction Software Beta Test
3rd Party Compliance Manager Pilots
Additions and Alterations Rules
Additions and Alterations Software Beta
New Construction Compliance Software
Additions and Alterations Software
Draft ACM Manual
Final Draft ACM Reference Manual
CEC Compliance Software Certification
Deadline for CEC Software Certification
Support
PAC Meeting
Workshop
7/17/2012
x
x
x
x
x
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Dec-13
Nov-13
Oct-13
Sep-13
Aug-13
Jul-13
Jun-13
May-13
Apr-13
Mar-13
Feb-13
Jan-13
Dec-12
Nov-12
Oct-12
Sep-12
Aug-12
Jul-12
Jun-12
May-12
Apr-12
Mar-12
Feb-12
Jan-12
Dec-11
Nov-11
Oct-11
Activities
Sep-11
Month of
CSE SIMULATION ENGINE STATUS

Energy calculation for “typical” buildings done and testing:

Integrated & improved 2008 attic and duct models

Multiple conditioned and unconditioned zones

Pressure flow inter zone air flow network for infiltration,
natural ventilation, mechanical ventilation and duct leakage

State of the art ASHWAT window model

Variable convective films and mass for all surfaces

Sky temperature and radiant heat transfer for all surfaces

Improved air conditioning model with latent load calculation
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CSE SIMULATION ENGINE STATUS

Not done yet:

HVAC sizing for the simulation

Central fan cooling ventilation (Nightbreeze etc.)

Other HVAC systems:

7/17/2012

Heat pumps

Hydronic and other unducted heating

Evaporative condensers
Multi-segment duct model
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ENERGY CALCULATION RULES
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

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Will be documented in the 2013 Residential ACM Reference
Manual following the Compliance Manager data model
organization
Prescribe the user inputs for compliance calculations
Explain how those inputs are used to set up the CSE and
DHW calculations for the Proposed and Standard Design
Specify the Reporting and Verification required
For this presentation, focus is on new rules and rules that
have changed

To accommodate new and improved algorithms

To respond to changes in the 2013 Standard
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RULES CATAGORIES

The Building/Project

Conditioned Zones

Attics

Other unconditioned zones
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THE BUILDING/PROJECT RULES

Standards Version

Dwelling Units

Solar

Construction Assemblies

Cooling and Heating Subsystems

Fan Subsystems

Distribution Subsystems

HVAC Systems

Ventilation Systems

Zoning

Air Leakage and Infiltration
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STANDARDS VERSION

New Input: Standards Version


Compliance 2014: through December 2014 (with current Federal Air
Conditioning efficiency requirements
Compliance 2015: any time (with 2015 Federal Air Conditioning
Requirements)

Standard Design: AC efficiency at specified Federal level

Reporting:

Standards Version

SEER & EER if Compliance 2015
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DWELLING UNITS

Inputs





For each dwelling unit type in the building input

Conditioned Floor Area (CFA)

Number of bedrooms
For Multi-Family input the number of each dwelling unit type
Calculate the Indoor Air Quality (IAQ) Ventilation CFM for
each unit type
Standard Design: Same Unit Types as Proposed Design
Reporting: Unit Types and minimum IAQ ventilation CFM’s
for verification.
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SOLAR

For single family and town houses if

standards version is “Compliance 2015”

and Zone is 9-15


Then input the kWdc of the proposed Photovoltaic
system (minimum 2 kWdc)
Calculate the PV compliance credit as the smaller of:


7/17/2012
PV Generation Rate (kTDV/kWdc) * kWdc
Max PV Cooling Credit * Standard Design Cooling
Energy (kTDV)
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SOLAR

PV Credit:
Climate
Zone
09
10
11
12
13
14
15
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PV Generation Rate
(kTDV/kWdc)
30269
30342
29791
29556
29676
31969
29536
Max PV Cooling Credit
(% of Standard Design
Cooling kTDV/ft2)
Maximum Impact
on Prototype
% of total TDV
13%
15%
18%
17%
17%
16%
19%
7%
8%
10%
6%
10%
9%
17%
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CONSTRUCTION ASSEMBLIES

Replaces 2008 Joint Appendix 4 U-factor Tables



U-factor is not an input to the CSE Simulation
Creates Layered constructions for CSE input

Material layers selected from CEC approved library

Flexible R values for insulation layers


U-factor calculated in Compliance Manager for
Prescriptive compliance and user feedback
Separate frame and cavity surfaces for frame
constructions
Reporting: to be determined
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COOLING SUBSYSTEMS
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Improved Cooling Algorithm


Adds calculation of indoor humidity and latent load
Evaporator air flow and conditions affect sensible heat
ratio

New relationship based on R410 refrigerant

New input for fan motor type: PSC or BPM

Drop cooling size credit

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
Little used

No consensus on calculation or energy savings
New input, algorithm and report for bypass duct (TBD)
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HEATING SUBSYSTEMS


Standard Gas Furnace algorithm unchanged from 2008
RACM (but the Federal minimum efficiency changes)
New air source heat pump algorithm, inputs and reporting
to be developed
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Fan Subsystems



Component of

Cooling and Heating systems

Ventilation Cooling systems

IAQ Ventilation systems
Inputs

CFM

W/CFM

Type (PSC, BPM)
Model
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
Fan operates at specified CFM in Airnet

Fan heat added to air stream
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Distribution Subsystems


Ducts in unconditioned spaces are an important component:

Cooling and Heating systems

Cooling, Heating and Ventilation systems
Same model as 2008 with added features:



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Multiple duct systems located in any zone (attic and crawl
for example)
Improved treatment of insulation thickness and conductivity
Duct segments for accuracy and to support input of reduced
area, buried ducts etc
Operates in ventilation mode to accurately model CFI IAQ
ventilation systems
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HVAC Systems

An HVAC system is a collection of one or more of the
following components:


cooling subsystem

heating subsystem

fan subsystem

Distribution subsystem
Examples


Split system cooling subsystem, gas furnace, PSC furnace
fan, ducts in attic

Whole house fan

Bathroom exhaust for IAQ ventilation
All components of a system use the distribution subsystem
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Cooling Ventilation Systems

Natural ventilation through openable windows

Mechanical Cooling Ventilation

Whole House Fan

Integrated Central Fan (Nightbreeze, Smartvent etc)
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Window Ventilation Cooling


Same inputs, defaults and reporting as 2008
Effectiveness reduced by 50% to reflect behavior and
experience

Available from dawn to 11 PM

Modeled as envelope holes in airnet
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Whole House Fan Ventilation Cooling


New measure for 2008

Input is total CFM of fans and W/CFM

Effectiveness reduced by 75% to reflect average behavior

Available from dawn to 11 PM (requires windows to be opened)

Modeled as exhaust fan from conditioned zone to attic in airnet

CFM and W/CFM from CEC fan listing
Standard Design and default:


2 CFM/CFA at 0.1 W/CFM in single family in Zones 8-14
Reporting: Proposed CFM and W/CFM
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Integrated Central Fan Ventilation Cooling

New measure for 2013


Available any hour of the day
Modeled as supply fan from outdoors to zones with relief to attic in
airnet

Controlled on current vent setpoints and indoor-to-outdoor delta T

Fixed speed systems (Smartvent etc) input fixed CFM and fan W

Variable speed systems (Nightbreeze, etc) use manufacturer
certified max CFM, W/CFM and off max functions

Reporting: Type, CFM, W/CFM

Verification:


Type, CFM & W/CFM at max flow
Duct leakage in air conditioning mode with damper normally closed
(but not specially sealed)
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Indoor Air Quality Ventilation Systems



Same functional requirements as 2008
New 2013 requirement to verify whole house outdoor
ventilation CFM for each dwelling unit.
Reporting:


Verification:

7/17/2012
Type, CFM for each dwelling unit, W/CFM
Type, CFM of outdoor air, and W/CFM if not default.
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Zoning the Building

Zoning the spaces in the building is optional (recommended
for added accuracy even for single zone systems)





A 40 ft2 opening will be assumed between adjacent zones
Building components such as ceilings, floors, walls, windows and
point source internal gains (such as the kitchen) must be assigned to
the correct zone
Heating and cooling, up to the CSE sized capacity of the system
assigned to the zone, are assumed to be delivered to each zone as
required to meet the scheduled set points.
The location of duct system return grills must be input
The Standard Design building has the same zoning as the proposed
design.
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Zonal Systems



The cooling system zonal thermostats are deleted and all
spaces operate in cooling at the conditioned zone set
points
The heating system zonal thermostats and schedule are
maintained for systems that meet the current
requirements for that credit
An algorithm will be developed to model the impact of
bypass ducts on cooling system performance
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Air Leakage and Infiltration





Envelope air leakage is a building level characteristic
Input is Air Changes at 50 Pascals (ACH50) measured
according to the CEC approved method (copied from
Resnet).
Default and Standard Design is

5 ACH50 for single family and multi-family homes

7 ACH50 for Townhouse leakage measured as a single unit
A lower value may be used for single family and
townhouses if verified
Reporting: ACH50 if other than default
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Envelope Air Leakage (ACH50)
11
10
9
Air Changes at 50 Pa
8
7
SF
6
Apartment
5
TownHouse
4
3
2
1
0
1
19
37
Air Leakage Distribution

Envelope air leakage is located at the building surfaces
% of Total House Leakage by Surface
Configuration
Slab on grade
Raised Floor
No Garage
Attached Garage
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Exterior
House to
Ceilings Floors Walls Garage Surfaces
50
0
40
10
50
0
40
10
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Leakage Location Single Family
10
9
8
7
ACH50
6
Other
5
4
3
2
1
0
Garage
Attic
Airnet Holes



The leakage in a surface is represented by 2 holes spaced
vertically at 25% and 75% of the height of the surface
If the air in the space is warmer than air outside, air
density (stack effect) causes air to flow in the bottom hole
and out the top hole.
If the air in the space is colder the flow goes the other way
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Wind and
Mechanical Effects



Holes are needed on each side because wind pressure is different
on each side of the building (upwind, downwind and parallel
sides assumed, wind is not orientation specific).
Fans and duct leaks change the pressure uniformly on the whole
space
The combined pressure on each hole is the sum of the wind,
stack and fan pressure (which may add or cancel each other)
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Multi-Zone





Gets pretty complicated…
There is also a hole
between each pair of
zones (door or stair)
Then we add Windows..
The Compliance Manager
calculates the size and
location of each hole
The Airnet calculation
finds the air pressure in
each zone that makes
the air flows in the entire
network balance
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CONDITIONED ZONES

Dimensions and Location

Internal Gains

Exterior Surfaces

Ceilings below Attics

Exterior Walls

Surfaces between Zones

Interior walls, ceilings and floors

Slab on grade floors

Raised Floors
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Zone Location and dimensions


Location and dimensions added for Airnet

Floor to floor height

Elevation of the bottom of the Zone

Window head height of the top windows
Zone types and thermostats are unchanged except

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The zonal cooling thermostats are deleted
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Surfaces




Surface inputs unchanged except for Construction instead of U-factor
Airnet holes automatically created in each wall, floor and ceiling.
Hole size proportional to area as fraction of total area of surface type
in building
Ceilings below Attics

Defined in the conditioned space zone below

Air net hole to attic automatically created in each surface
Floors, roofs and ceilings between zones



Dimensions and constructions must be entered in one zone
Openings defaulted to 40 square feet between conditioned zones
in the same dwelling unit
Air net holes to unconditioned zone automatically created in each
surface
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Windows

Window and skylight inputs and reporting unchanged

Shade operation for windows


7/17/2012
Interior shades half open during day, 80% closed at night
Automatically operated exterior shades closed when air
conditioning. Rules to be developed.
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Thermal Mass

Inside the zone light mass and surfaces are fixed:

Light mass (Cair) is 2 BTU/CFA

Interior wall with one side area equal to CFA

Interior floor if multi-story zone


7/17/2012
Furniture made of 2.5” wood with one side are equal to 2 times
the CFA
No change to slab floors (default 80% carpet, 20% bare)
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HERS II Internal Gain

Internal gains according to HERS II formulas and schedule



Appliance efficiency and fuel types default in both Proposed and
Standard Design
If multi-zone, specify the zone where point sources (such as
kitchen) are located
Added latent fraction to HERS II gains:
Sensible
Lights
People
Misc
Refr
Dishwash
cook
Washer
Dryer
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Latent
1
0.573
0.97
0
0.427
0.03
1
0.75
0.33
1
0.5
0
0.25
0.67
0
0.5
40
Sensible Internal Gain Comparison
Fig. 3. 2700 ft2 4 BR Prototype Average Internal Gain
5,000
4,500
Lights
Equip
People
Refrig
Internal Gain (Btu/h)
4,000
3,500
3,000
2,500
2,000
1,500
1,000
500
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
Time of Day
5,000
4,500
HERS II
Internal Gain (Btu/h)
4,000
2008 RACM
3,500
3,000
2,500
2,000
1,500
1,000
500
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
Time of Day
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UNCONDITIONED ZONES


Attic

Floor Area

Ventilation

Attic Edge
Other zones (optional)

Crawl Spaces

Basements

Garages
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Attic

Attic floor area defined by ceiling areas of zones below

Attic ventilation is no longer a compliance variable



1/300 soffit ventilation assumed
Vent area increased if needed to provide a minimum of CFM/375
ft2 free area for cooling ventilation fan relief
Insulation in the attic

Input is R value

Insulation type (cellulose, fiberglass, foam, etc) is not a variable

Assume R = 2.6/inch (light blown fiberglass)
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Attic Edge - Not Part of the Attic
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Attic Edge

Solution is to treat the attic edge area as a cathedral ceiling

No heat flow to the attic from this area

Attic floor area (and volume) reduced by the edge area

Tapered insulation cross section (and truss path) on left
above can be approximated by 2 rectangular sections on the
right that provide nearly the same steady state heat flow
and can be simulated as a 1 dimensional surfaces in CSE
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Attic Edge

Inputs

Roof Pitch

Distance from top plate to roof deck, default 3.5”

Ceiling Insulation and Below deck insulation R

Length of attic edge

For simplicity not an input

Assume 3 times the square root of Attic Floor Area

Compliance Manager generates the cathedral surfaces

Standard Design: default geometry with Prescriptive R

Reporting: Heel height for verification if not defaulted
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Other Unconditioned Spaces

Modeling (optional) for improved accuracy and flexibility

Crawl Spaces

Basements

Garages

Rules to be developed

Default: Current rules (not modeled as zones)

Standard Design: Same modeling as proposed

Reporting: to be developed
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Other RACM Topics To Be Developed

Domestic Hot Water

Additions/Alterations

Testing
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