ashrae standard 90.1 and building energy simulation … · • step 4: model the budget design to...

ASHRAE Standard 90.1 andBuilding Energy Simulation

BEAM Pro Mandatory CPD Training

14 June 2012 (Thu)

Copyright © 2012. All right reserved

Overview

Overview

• Instructors/Speakers:• Dr. Sam C. M. Hui

• Teaching Consultant and Honorary Assistant Professor, Department of Mechanical Engineering, The University of Hong Kong

• Dr. JIANG Wei• Associate Director of Sustainability Engineering, WSP

Hong Kong Ltd

Overview

• Dr. Sam C. M. Hui• PhD, BEng(Hons), CEng, CEM, MASHRAE, MCIBSE,

MHKIE, MIESNA, LifeMAEE, AssocAIA• ASHRAE Distinguished Lecturer (2009-2011)• CEng = Chartered Engineer• CEM = Certified Energy Manager• LifeMAEE = Life Member, Associatn of Energy Engineers• Worked in 1998 as a visiting researcher in the Asia Pacific

Energy Research Centre, Japan• Research interests: energy efficiency in buildings and

sustainable building technologies

Overview

• Date and Time:• 14 June 2012 (Thu), 9:30-12:30 & 14:00-17:00

• Venue:• Hong Kong Convention and Exhibition Centre

• Course Content• ASHRAE Standard 90.1• Appendix G for building energy performance

rating• Key concepts of building energy simulation• Building energy software

Overview

• Learning outcomes:- after completing this workshop, you should know:• Basic concepts of ASHRAE Standard 90.1 and

how to use it for green building certification• How to apply Appendix G of the standard to

simulate building energy use• Key concepts of building energy simulation• How to use building energy software for green

building design and analysis

Overview

• A technical guide “Standard 90.1-2010 User’s Manual” from ASHRAE*• List price at US$99

• Available at www.ashrae.org• Most relevant chapters in the guide:

• 11. Energy Cost Budget Method• G. Performance Rating Method

• Related chapters in the guide:• 6. HVAC Systems• 9. Lighting

* ASHRAE = American Society of Heating, Refrigerating and Air-Conditioning Engineers

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Dr. Sam C. M. HuiE-mail: [email protected]

ASHRAE Standard 90.1



14 June 2012 (Thu)

Contents

• Introduction• Structure and Scope• Compliance Options• Energy Cost Budget Method• Performance-based Code• ASHRAE 90.1 and LEED

Introduction

• ASHRAE Standard 90.1• Energy Standard for Buildings Except Low-Rise

Residential Buildings• SSPC 90.1 Standing Standard Project Committee

• Purpose: provide minimum requirements for the energy-efficient design of buildings except low-rise residential buildings

• Not a design or advanced building guide• Separate advanced energy design guides were

developed by ASHRAE and other related bodies

Introduction

• Why ASHRAE Standards 90.1 is important?• It is the reference standard for US Energy Policy

Act and many building energy codes in USA• It has been adopted in many countries as a model

for energy efficiency guidelines and codes• It is the professional “standard of care” set by

ASHRAE consensus, with support from• IES (Illuminating Engineering Society)• ANSI (American National Standards Institute)

• Required for LEED certification

Introduction

• US Energy Policy Act requires State codes to meet or exceed 90.1 (different versions)• It becomes law when the States adopt it

• Other codes or standards also refer to it, e.g.• International Energy Conservation Code (IECC)• NFPA 5000• Federal codes• State or local specific codes (e.g. California

Title24)

Introduction

• ASHRAE 90.1 timeline:• 90-1975: first issued• 90A-1980: updated• 90.1-1989: updated• 90.1-1999: major rewrite• 90.1-2001: minor revisions• 90.1-2004: updates, reorganization• 90.1-2007: updates

See also: http://en.wikipedia.org/wiki/ASHRAE_90.1

Introduction

• ASHRAE 90.1-2010 (current version)• Goal: to achieve 30% energy savings compared to

90.1-2004 (may not be met for all buildings types in all locations)

• Standard 90.1 is on a 3-year cycle under a “continuous maintenance process”• Ongoing changes through “addenda”• Consensus standard (open ANSI process)

• Jointly sponsored by IES and ANSI

Introduction

• Different versions of ASHRAE 90.1• 90-1975

• Earliest version (in response to energy crisis)• 90A-1980 (w/ 90B-1975 and 90C-1977)

• Modified & included lighting procedure from IESNA• 90.1-1989 and 1993 codified version of 1989

• Significant change in envelope compliance• Towards a building energy performance standard• Upgrades in lighting and HVAC requirements

Introduction

• Different versions of ASHRAE 90.1 (cont’d)• 90.1-1999/2001

• Changes in format and technical content• Written in mandatory, enforceable language• Expanded climatic data to international locations• Both IP and SI units included

• 90.1-2004• Envelope and mechanical requirements expressed using

new climate zones• Lighting requirements more stringent by about 25%• Entire document has been reformatted

Introduction

• Different versions of ASHRAE 90.1 (cont’d)• 90.1-2007

• Incorporate 42 addenda• Further reduction in lighting power densities• Fan power limitation is based on either nameplate

horsepower, or system brake-horsepower• Fan pressure drop adjustment & VAV fan control

• 90.1-2010• Incorporate 60+ addenda, elevator was included

• 90.1-2013 (proposed)• Expand to new areas; holistic building design

Introduction

• Related ASHRAE Standards• 90.2-2007: for low-rise residential buildings• 100-2006: energy conservation in existing buildings• 105-2007: standard methods of measuring, expressing and

comparing building energy performance• 140-2007: evaluation of building energy analysis computer

programs• 169-2006: weather data for building design standards• 55-2010: thermal comfort standard• 62.1-2010: ventilation for acceptable indoor air quality• 189.1-2011: high performance green buildings

ASHRAE 90.1 development process

(Source: US Department of Energy)

CommitteeProposesStandardChanges

PublicReview

andComment

CommentAccepted

CommitteeApproval

ASHRAEBoard ofDirectorsApproval

ANSIApproval

NewStandards

or AddendaPublished

SubstantiveChanges

Appeal ofCommitteeApprovalupheld denied

Code compliance and the building process in USA

Save Energyand Money

Reduce CarbonEmissions

LocalGovernment

LocalGovernment

LocalCodeLocalCode

ArchitectsBuilders and

Engineers

BuildingConstruction

Review PlansReview products, materialsequipment specificationsReview tests, certificationreports, product listingsInspect building and itssystems during constructionEvaluate materialssubstituted in the fieldInspect prior to occupancy

StateGovernment

StateGovernment

StateCodeStateCode

C O M P L I A N C E

BuildingEnergy Code

BuildingEnergy Code


Structure and Scope

• Structure of Standard 90.1-2010• Section 1 - Purpose• Section 2 - Scope • Section 3 - Definitions, Abbreviations, and

Acronyms• Section 4 - Administration and Enforcement • Section 5 - Building Envelope • Section 6 - Heating, Ventilating, and Air

Conditioning

Structure and Scope

• Structure of Standard 90.1-2010 (cont’d)• Section 7 - Service Water Heating • Section 8 - Power• Section 9 - Lighting• Section 10 - Other Equipment • Section 11 - Energy Cost Budget Method • Section 12 - Normative References

Structure and Scope

• Standard 90.1-2010 Appendices• A – Rated R-Value of Insulation and Assembly U-

Factor, C-Factor, and F-Factor Determinations• B – Building Envelope Climate Criteria• C – Methodology for Building Envelope Trade-

Off Option• D – Climatic Data• E – Informative References • F – Addenda Description Information• G – Performance Rating Method

Building envelope

Structure and Scope

• Purpose: provide minimum requirements for the energy-efficient design of buildings except low-rise residential buildings

• Not a design or advanced building guide• Separate advanced energy design guides were

developed by ASHRAE and other related bodies• Consensus standard (open ANSI process)

• Jointly sponsored by IESNA and ANSI* IESNA = Illuminating Engineering Society of North America (now IES)

ANSI = American National Standards Institute

Structure and Scope

• Scope• New buildings and their systems• New portions of buildings and their systems

(additions)• New systems and equipment in existing buildings

(alterations), e.g. computer rooms• Exemptions, such as

• Equipment and portions of building systems that use energy primarily for industrial or manufacturing purposes

Structure and Scope

• Main areas• Building Envelope

• Roofs, walls, floors, slabs, doors, vertical glazing, skylights• HVAC Equipment and System

• Cooling equipment efficiency, heating equipment efficiency, supply fans, ventilation control, ducts

• Lighting• Interiors electric lighting, controls, daylighting

• Services Water Heating (SWH)• Equipment efficiency, pipe insulation

• Power and others• Motors, plug loads

ASHRAE 90.1 compliance approaches

Mandatory Provisions(required for most

compliance options)

Building System Compliance Options

Energy Code Compliance

Prescriptive Option

Energy Cost Budget

Trade Off Option

Simplified

Envelope

HVAC

Lighting

SWH

Power

Other


Envelope compliance options in ASHRAE 90.1

MandatoryProvisions

Trade-off OptionPrescriptive

OptionEnergy Cost

Budget

Compliance

Compliance Options

• Building envelope prescriptive option:• Window-to-wall ratio (WWR) ≤ 40%, skylight-

roof ratio ≤ 5%• 8 Criteria sets for different climate types

• Insulation level, fenestration criteria• Building envelope trade-off option:

• Envelope performance factor (EPF) of proposed building ≤ EPF of budget building• ENVSTD and ComCheck software

HVAC compliance paths


Compliance Options

• HVAC simplified approach option:• Limited to small buildings (< 2,500 sq.m)

• HVAC mandatory provisions:• Minimum equipment efficiency• Load calculations• Controls• HVAC system construction and insulation• Completion requirements

Compliance Options

• HVAC prescriptive path:• Economizers• Simultaneous heating and cooling limitation• Air system design and control• Hydronic system design and control• Heat rejection equipment• Energy recovery• Exhaust hoods, radiant heating systems• Hot gas bypass limitation

Lighting compliance requirements

Exemptions

Mandatory Requirements (Interior and

Exterior)

Controls

Switching

Interior Lighting Power

Limits

Whole Building

Additional Allowances

+

Efficiency

Space-by-Space

Exemptions

Exterior Lighting

Power Limits+

Total Connected

Power

Interior Lighting Power

Allowance<

OR

Tradable

Non-Tradable

Total Connected

Power

Exterior Lighting Power

Allowance<


Compliance Options

• Interior lighting power• Building area method

• For whole building, grossed area• Space-by-space method

• For projects w/ well defined space types• Exterior lighting power

• Lamp efficacy• Exterior lighting power wattage limits

Compliance Options

• How were the Lighting Power Densities (LPD) developed?• Basis: A space type lighting design modeling that applies:

• Current lighting product performance data• Current lamp/ballast efficacy and light loss factors• Latest IESNA recommended light levels• Professional consensus of quality lighted environments

• Combine these elements into building space models to calculate lighting power densities

• Apply space type LPDs to real building data to generate whole building LPDs

Compliance Options

• Service Water Heating• Prescriptive and energy cost budget• Mandatory provisions (Section 7.4)

• Load calculations• Equipment efficiency• Service hot water piping insulation• System controls• Pools• Heat traps

• Prescriptive path (Section 7.5)• Space heating and water heating• Service water heating equipment

Compliance Options

• Power and Other Equipment• Max voltage drop allowed at design load

• Feeder conductors• Branch circuit conductors

• Motor efficiency levels correspond to Energy Policy Act’s manufacturing standards

• Mandatory provisions are for General Purpose Design A and Design B motors only

• Motors in new buildings, additions to existing buildings, and alterations to existing buildings must comply

Energy Cost Budget Method

• Energy Cost Budget (ECB) Method• The ultimate trade-off method to trade-off across

building systems through the use of annual, hourly simulation tools and a baseline building

• The only real way to deal with unique designs, renewables, high-efficiency equipment, etc.

• Buildings must still meet all mandatory requirements

• Basis of performance-based codes


• ECB method’s Pros and Cons• User sophistication• Enforcement sophistication• Better buildings• Aging of the standard• Gamesmanship• Cheating• Innovation

Basic concept of Energy Cost Budget (ECB) Method

(Source: Hawaii building energy code)

Energy Cost Budget (ECB) Method in ASHRAE 90.1


• Step 1: Verify compliance with the mandatory provisions of Standard 90.1

• Step 2: Determine which prescriptive requirements to implement

• Step 3: Model the proposed design in accordance with Section 11.3 of Standard 90.1

• Step 4: Model the budget design to determine the annual energy cost budget

• Step 5: Compare the annual energy costs of the two models


• Budget design (reference building)• Based on the proposed design, but changes all

Standard 90.1-governed design details to represent minimum compliance, e.g.

• Building envelope characteristics• Lighting power densities• Economizer type (if required)• Heat-recovery type (if required)• HVAC system type• Fan energy, cooling & heating equipment


• Typical requirements by authorities• Must document all the info in great detail• Must use a good and approved simulation program• Must use appropriate and approved climate data• Must use appropriate and approved purchased

energy rates• All details not covered by the 90.1 must be

identical in both models• ECB method compliance forms


• Building Performance Rating Method• Appendix G• Instructions for using the ASHRAE Standard

90.1-2010 Energy Cost Budget Method in conjunction with the LEED program

• LEED = Leadership in Energy and Environmental Design (developed by US Green Building Council)

• ECB forms the basis of the energy portion of the LEED rating

Performance-based Code

• Building Energy Codes (BEC)• Set out minimum energy consumption objectives• Form part of the energy policy• Control building design and/or operation

• Energy audit requirements (in some countries)• Essential for existing buildings

• Energy management programmes• Promote good practices in design and operation


• Basic functions of BEC:• Raise concerns and awareness of energy efficiency• Promote energy efficient design & operation• Facilitate energy conservation products & services• Provide a basis for building energy performance• Help achieve energy policy goals

• Code requirements• Prescriptive approach• Performance approach


• Prescriptive approach• Specifies for each building component the

minimum requirements to satisfy the code• Advantages:

• Simple to use & follow• Easy to check & enforce

• Drawbacks:• Rather restrictive• Barrier to innovation & performance optimisation• Hinder cross-country product trading


• Performance approach• State the goal(s) and allows the use of any solution

to demonstrate compliance• Advantages:

• More clearly explains what the code intends• Permits innovation & alternative solutions• More flexible regulatory environment, easily updated• Encourage building/technology research

• Drawbacks:• Often more efforts are needed for analysis/compliance• Can be very complex & require more expertise

The triangle of performance-based approach

Proposed Building Design

Designed Building

Design EnergyConsumption

Reference Building

Total EnergyBudget

Consumption≦ budget?

Compliance with the buildingenergy code

Yes

BuildingDescription

Building EnergyAnalysis

PerformanceComparison

CodeCompliance

Basic requirementsmust be met

Performance compliance for building energy code

符合建築節能規範規定

Proposed design

Basic requirements

Prescriptiverequirements

System performancerequirements

Whole buildinganalysis method

Comply? No

Compliance paths in building energy codes

Yes

Total Building EnergyPerformance

PrescriptiveApproach

PerformanceApproach

Compliance for the Proposed Design

BuildingEnvelope Lighting HVAC Electrical Lift &

Escalator

BasicRequirements

Building EnvelopeLightingHVAC

ElectricalLift & Escalator

Proposed framework of the comprehensive BECs in Hong Kong

(Source: EMSD)

Qgs

(glass solar)

Qwc

(wallconduction)

Qgc

(glassconduction)

i

fffeqww

i

gsgcwci

ASFSCADTUATDUA

AQQQ

OTTV

)()()(

Characteristics of BEC

• OTTV equation for Hong Kong:

• Two major differences from the general form:• Glass conduction term was omitted• Solar absorptivity and external shading multipler

were introduced

i

feqwwi A

SFESMSCATDUAOTTV

)()(

Building Energy Codes in Hong Kong(Source: www.emsd.gov.hk)

Building energy codes in Hong Kong

OTTV

Lighting

Air conditioning

Electrical

Lifts & escalators

Performance-based code

Jul 1995 (Mandatory)

Jul 1998 (Voluntary)*

Jul 1998 (Voluntary)*

Feb 1999 (Voluntary)*

Dec 1999 (Voluntary)*

2004 (Voluntary)*

Energy Code Date Implemented

Comm bldgs & hotels

All bldgs except domestic, indust. & medical

All bldgs except domestic, indust. & medical

All buildings

All buildings

Comm bldgs & hotels

Scope

* Combined and become mandatory in 2011 under the Buildings Energy Efficiency Ordinance. (See www.emsd.gov.hk/emsd/eng/pee/mibec.shtml for details)

(Source: www.emsd.gov.hk)

ASHRAE 90.1 and LEED

• LEED Green Building Rating System• Leadership in Energy & Environmental Design• By US Green Building Council• Current LEED systems:

• New construction & major renovation (LEED-NC)• Existing building operations (LEED-EB)• Commercial interiors projects (LEED-CI)• Core and shell projects (LEED-CS)• Schools, Retail, Healthcare, Homes• Neighborhood development (LEED-ND) (in pilot)


• LEED Green Building Rating System• Evaluates and recognizes performance in accepted

green design categories, including:• Sustainable sites• Water efficiency• Energy and atmosphere• Materials and resources• Indoor environmental quality• Innovation credits

• Website: www.leedbuilding.org


• LEED Green Building Rating System• Whole-building approach encourages & guides a

collaborative, integrated design & construction process • Optimizes environmental and economic factors

• Four levels of certification (for version 2 or before)• LEED Certified 26 - 32 points • Silver Level 33 - 38 points • Gold Level 39 - 51 points • Platinum Level 52+ points (69 possible)

• LEED Accredited Professional


• LEED version 3 and new schemes• Include other criteria

• Locations & linkages• Awareness & education• Regional priority

• LEED Professionals• LEED Green Associate• LEED AP (different types)

• Bldg design & construction, O&M, Homes, Interior design, Neighborhood development


• Credits in LEED 2009 NC:• Sustainable Sites (SS)• Water Efficiency (WE)• Energy and Atmosphere (EA)• Materials and Resources (MR)• Indoor Environmental Quality (IEQ)• Innovation in Design (ID)• Regional Priority (RP)

(Source: USGBC) For LEED version 3


• Prerequisite (New Construction)• SSp1: Construction activity pollution prevention• WEp1: Water use reduction• EAp1: Fundamental commissioning of building

energy systems• EAp2: Minimum energy performance• EAp3:Fundamental refrigerant management• MRp1: Storage and collection of recyclables• IEQp1: Minimum IAQ performance• IEQp2: Environmental tobacco smoke control


• LEED 2009 NC award scale:• Platinum 80 points and above• Gold 60–79 points• Silver 50–59 points• Certified 40–49 points

• Credit weightings• Based on the potential environmental impacts and

human benefits of each credit with respect to a set of impact categories

(Source: USGBC)

LEED 2009 New Construction Checklist (cont’d)


• EAp2: Minimum energy performance• Intent: Establish the minimum level of energy

efficiency for the proposed building and systems• Requirements: Mandatory provisions of 90.1 and

• Prescriptive requirements of 90.1 or• Performance requirements of 90.1 Section 11 (Energy

Cost Budget Method) or• The requirements in the local energy code, whichever is

more stringent


• EAc1: Optimize energy performance• Intent: Achieve increasing levels of energy

performance above the baseline in the prerequisite standard to reduce environmental impacts associated with excessive energy use

• Requirements: Awards points for improving performance rating of the design building vs. baseline building as per ASHRAE Standard 90.1 (Appendix G) [1 to 19 points]

Dr. Sam C M HuiE-mail: [email protected]

Appendix G for building energy performance rating



14 June 2012 (Thu)

Contents

• General Information and Scope• Performance Rating• Simulation Requirements• Building Performance Calculations• Major Considerations

ASHRAE 90.1 compliance approaches

Mandatory Provisions(required for most

compliance options)

Building System Compliance Options

Energy Code Compliance

Prescriptive Option

Energy Cost Budget

Trade Off Option

Simplified

Envelope

HVAC

Lighting

SWH

Power

Other


General Information and Scope

• For 90.1-2010, Appendix G is now a normative section (previously informative)• It incorporates Appendix G fully into the standard

making it subject to the same rigorous public review process the rest of the standard undergoes

• Using 90.1 as baseline for energy efficient and green building programmes• Use performance rating method to calculate

energy savings; give credits to advanced design strategies, more flexible than ECB method


• Understand the intent and limitations• Intended for rating only; not for code compliance• Provide a baseline for comparison & rating• Not to accurately predict actual energy use/costs

• Factors affecting absolute accuracy:• Variations in occupancy• Variations in control and maintenance• Variations in weather• Changes in energy rates• Precision of the simulation software

Energy Cost Budget Method(from 90.1 Section 11 for EAp2)

Performance Rating Method(from 90.1 Appendix G for EAc1)

Calculates at least 1,400 hours of building operation to simulate annual energy use

Calculates 8,760 hours of building operation to simulate annual energy use

Accounts for hourly variations (defined separately for each day of the week and holidays) in occupancy, lighting power, miscellaneous equipment power, thermostat setpoints, and HVAC operation

[Same]

Accounts for thermal mass effects [Same]

Models 10 or more thermal zones [Same]

Accounts for part-load performance ofmechanical equipment

[Same]

Includes capacity and efficiency corrections for mechanical cooling & heating equipment

[Same]

Models airside and waterside economizers with integrated control

Models airside economizers with integratedcontrol

Comparing the simulation requirements for ECB & PR methods

Energy Cost Budget Method(from 90.1 Section 11 for EAp2)

Performance Rating Method(from 90.1 Appendix G for EAc1)

Models budget building design characteristics per Section 11.5

Models baseline building design characteristics per Section G3

Calculates design loads [Same]

Uses hourly weather data, such as temperature and humidity, for the climate that best represents the location of the proposed design

[Same]

Calculates annual energy costs using rates forpurchased energy approved by the adoptingauthority; or, exports hourly reports of energyuse to a program that can

Calculates annual energy costs using eitheractual rates for purchased energy or stateaverage energy prices published by DOE’sEnergy Information Administration, http://www.eia.doe.gov/; or exports hourly reportsof energy use to a program that can

Tested in accordance with ASHRAE Std 140-2007, Standard Method of Test for the Evaluation of Building Energy Analysis Computer Programs

Includes calculation methodologies for thebuilding components being modeled

Comparing the simulation requirements for ECB & PR methods (cont’d)


• Trade-off limits• Does not allow energy savings based on promises

about the future or measures made in the past• Savings must be based on “real time” conditions

• Documentation requirements• Project summary & project overview• Energy efficiency features• Mandatory features• Prescriptive tradeoffs• Energy results


• Documentation requirements (cont’d)• Exterior shading• Floor plans and elevations• Thermal blocks• Modeling assumptions• Back-up calculations• Input and output reports• Energy rates• Explanation of error messages• Exceptional calculation methods

(Source: USGBC)

LEED 2009 New Construction Checklist (cont’d)


• EAp2: Minimum energy performance• Option 1: performance compliance path

• Mandatory provision (5.4, 6.4, 7.4, 8.4, 9.4, and 10.4)• Baseline building complies with Appendix G Building

Performance Rating Method• 10% better than 90.1-2007 for new construction, 5%

better for existing building


• EAp2: Minimum energy performance (cont’d)• Option 2: prescriptive compliance path

• ASHRAE Advanced Energy Design Guides (AEDG)• Small office buildings 2004• Small retail buildings 2006• Small warehouses and self-storage buildings 2008• K-12 school buildings 2010

• Option 3: prescriptive compliance path• Advanced Buildings “Core Performance” Guide by

New Building Institute

Performance Rating

• Use the PR Method to quantify energy savings• Like the ECB Method, the PR Method relies on

computer modeling to simulate the energy performance of two designs:

• Proposed Building vs Baseline (Reference) Building• Slight modifications as compared to ECB model:

• Includes receptacle and process energy consumption• Takes credit for automatic lighting controls in the

proposed design, either in accordance with Table G3.2 or via modified lighting schedules

Performance Rating

• Use the PR Method to quantify energy savings• Slight modifications vs ECB model (cont’d):

• Averages the performance of the baseline building at its actual orientation and when rotated 90°, 180°, and 270°. For each of the rotated simulations, the cooling and heating equipment are resized to 1.15 and 1.25 times the design capacity, respectively

• Uses lightweight assembly types for opaque assemblies, and U-factors, F-factors, and C-factors corresponding to weather/location-dependent values in Tables 5.5-1 through 5.5-8 of the standard

Performance Rating

• Use the PR Method to quantify energy savings• Slight modifications vs ECB model (cont’d):

• Models vertical fenestrations as evenly distributed bands of glass on all building orientations and limits them to not more than 40% of the above-grade wall area

• Calculates fan and pump energy in accordance with the equations in Appendix G

• Uses the appropriate HVAC system type (cooling, heating, and fan control types) from Tables G.3.1.1A and G.3.1.1B

Performance Rating

• The PR Method can be used for:• New construction and major renovations• Alterations or additions to existing buildings

• Points to note:• Systems that aren’t yet designed or that already

exist and are unmodified must be modeled identically for the proposed and baseline buildings

• If the proposed design includes future building components, then the components must be modeled as conforming to the minimum prescriptive requirements of 90.1

Performance Rating

• The proposed building design should model:• All end-use loads• Any energy-saving strategies (e.g. daylighting and

natural ventilation), where applicable• Actual lighting power if the lighting system

already is designed, or the lighting power allowance in accordance with Section 9 of 90.1

• Energy-saving architectural features, e.g. light shelves, overhangs, and other shading devices

• Any undesigned systems as identical to the baseline building design

Simulation Requirements

• The performance of both building models must be calculated using• The same weather data• The same energy rates• The same simulation software

• Performance rating method compliance forms• Project name and information• Advisory messages• Performance rating result• Energy use and energy cost summary


• Many software tools in the market• From simplified to complicated one• Select according to the task

• For beginners, we recommend• Energy-10, HAP, TRACE 700, eQUEST

• For sophisticated study, may consider• DOE-2, EnergyPlus, ESP-r, TRNSYS

• Further information:• Building Energy Software Tools Directory (by US-DOE)

• http://www.eere.energy.gov/buildings/tools_directory/

TRNSYS

TRACE 700

DOE-2

E-20-II & HAP

ESP-r

Building EnergySimulation Software

Solar-5ENERGY-10

EE4

eQUESTVisualDOE

Buildingdescription

Simulationoutputs

Simulation tool(computer program)

Weatherdata

- physical data- design parameters

- energy consumption (MWh)- energy demands (kW)- environmental conditions


• Requirements for simulation software:• Software must be approved by the adopting

authority & conform explicitly to the modeling requirements in Section 11 and Appendix G

• Most of the capabilities required to model the Energy Cost Budget (ECB) Method and the Performance Rating (PR) Method are identical

• Examples of suitable software: TRACE700, DOE-2, EnergyPlus, BLAST and Carrier HAP

• If the software cannot adequately model some aspect of the design, the authority may approve an “exceptional” calculation method

Modeling requirements for the Performance Rating Method (1)Model element Proposed building design Baseline building design

Building configuration, size

Consistent with design documents Number of floors and conditioned floor area matchesproposed design

Space use classification

Specify a single building type (per Section 9.5.1), unless the building is a mixed-use facility; or one or more spacetype classifications (per Section 9.6.1)

Same as proposed design

Schedules Hourly variations in occupancy, lighting power, miscellaneous equipment power, thermostat setpoints, and HVAC system operation are typical of the proposed building typeException: May model energy-saving strategies if approved by the rating authority

Same as proposed design … unless the proposed design models nonstandard efficiency measures

Model all conditioned spaces as both heated and cooled



Building envelope

Consistent with architectural drawings (or “as-built” forexisting buildings)

Dimensions: Exterior envelope components, roofs, doors, floors, and exposed perimeters of concrete slabs on grade are equivalent to proposed designOpaque assemblies: Use lightweight assembly types and U-factors, F-factors, and C-factors from Tables 5.5-1 through 5.5-8Vertical fenestration: Model as 40% of the above-grade wall area (or equal to the proposed design, whichever is smaller), configured as horizontal bands distributed uniformly across all orientations

Include effects of automated shades/blinds andpermanent shading devices, such as fins, overhangs, andlight shelves

Omit effects of shading projections, manual window shading devices, and self-shading of the building due to orientation


Lighting Use actual lighting power if the system exists; or lighting power allowance in accordance with Sections 9.1.3 and 9.1.4 if the system is designed; or lighting power in accordance with the Building Area Method if the lighting system is yet to be specified

Use the maximum lighting power allowed for the building or space-type classification(s) in the proposed design

Includes task, furniture-mounted, parking garage, and façade lighting


Account for automatic lighting controls, such as daylighting

Excludes automatic lighting controls(The baseline lighting schedule reflects the mandatory control requirements in Standard 90.1)


Thermal blocks (HVAC zones)

Model each HVAC zone as a separate thermal block


HVAC systems Model HVAC system, equipment, and controls types as designed. If no heating and/or cooling system exists, then system characteristics match those in baseline model

Use HVAC system types and descriptions specified in Tables G3.1.1A, G3.1.1B, and in Sections G3.1.2 and G3.1.3 For fan and pump energy, use values specified in Sections G3.1.2 and G3.1.3

Receptacle and other loads

Use estimates based on the building- or space-type classification

Same as proposed designException: Use the lowest allowable efficiency for components subject to the efficiency requirements in Section 10


• Table G3.1:–• Schedules: Changes to schedules allowed for

energy efficiency measures, e.g.• Lighting controls• Natural ventilation• Demand control ventilation (DCV)• Measures that reduce service water heating loads


• Table G3.1 (cont’d.)• Building Envelope:

• Baseline Building orientation and fenestration locations normalized in model

• Baseline Envelope meets code requirements for common construction type (lightweight assembly)

• Only automatically controlled shading devices may be modeled


• Table G3.1 (cont’d.)• Lighting:

• Model daylighting via software or schedules• Lighting Controls – Table G3.2 or schedules

• HVAC Systems• Per Tables G3.1.1A and G3.1.1B

Systems (air-side)

Plant (water-side & refrig.)

HVAC air systems HVAC water systems

Energy input by HVAC plant

Energy input by HVACair/water systems

Energy storage

Energy inputby appliance

Thermal Zone

Building energy simulation process

INPUTS:- Weather data- Building geometry- Construction type- HVAC type / usage- Occupancy info

- Quantity of users- Lights- Equipment- Usage

OUTPUTS:- Space temperatures- Surface temperatures- Humidity levels- HVAC parameters- Energy consumption

- Component- System- Whole-building

Building energy simulation: Inputs and Outputs

Garbage In, Garbage Out (GIGO)

Bldg Performance Calculations

• Step 1: Model the proposed design in accordance with Section G3

• Step 2: Model the baseline design• Step 3: Calculate the energy performance of the

proposed design• Step 4: Calculate the energy performance of the

baseline design• Step 5: Calculate the performance improvement of

the proposed design• Step 6: Verify model accuracy

Example: VisualDOE DOE-2

Example: VisualDOE DOE-2 Example: VisualDOE DOE-2



Major Considerations

• Document the results:• USGBC defines submittal requirements for each

of the prerequisites and credits for LEED• LEED submittal template• Supporting documentation

• Evidence required to support EAp2 and EAc1:• Calculated values for baseline and proposed building

performance• A list of all energy-related features in the actual design,

with the differences between the two models clearly identified


• Document the results:• Evidence to support EAp2 and EAc1: (cont’d)

• Simulation results that break down energy usage (at minimum) by lights, internal equipment loads, service water heating equipment, space heating equipment, space cooling and heat rejection equipment, fans, and other HVAC equipment (such as pumps)

• Simulation results showing the amount of time that any loads are not met by the HVAC system in each model

• An explanation of errors, if any, reported by the simulation software in the simulation results


• Documentation checklists• Input quality control checklist• Output quality control checklist• Output-input consistency checklist

• Non-typical energy systems & scenarios• Exceptional calculations• Calculations for additions to existing buildings• Calculations for multiple Buildings• District energy systems• Combined heat and power (CHP) systems

(Source: USGBC)


• Related LEED credits:• EA Credit 2, On-Site renewable energy• EA Credit 6, Green Power

• Exceptional calculation: examples• Natural ventilation• Process loads• Domestic hot water heat recovery• Domestic hot water reduction energy savings• Interior lighting controls

ashrae standard 90.1 and building energy simulation … · • step 4: model the budget design to...

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