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Beyond code compliance, but doable
This prerequisite is a big one, not only because it’s required for all projects, but also because it feeds directly into EAc1: Optimize Energy Performance, where about a fifth of the total available points in LEED are at stake. Master these minimum requirements, and you can use the same compliance path as in EAp2 to earning points.
You won’t earn the prerequisite by accident, though. Although “energy efficiency” is on everyone’s lips, the mandatory and performance-based requirements for EAp2 go beyond code compliance in most places. That said, there is nothing to stop you from meeting the requirements with a reasonable amount of effort, and the environmental benefits as well as the operational cost savings are significant.
Most projects start by choosing which of the three available compliance paths to follow. We’ll look at them each in turn.
Option 1: Energy modeling
Option 1 alone gives you access to all of the points available through EAc1, and offers the most flexibility in giving you credit for innovative designs.
First, you need to meet the mandatory requirements of ASHRAE 90.1-2007 for all major components, including the envelope, HVAC, lighting, and domestic hot water. ASHRAE 90.1 has had some changes and new mandatory requirements since the 2004 version, which was referenced on previous LEED systems, so be sure to review the standard carefully.
Energy efficiency is an area where it behooves project teams to start early and work together to maximize savings. Playing catch-up later on can be costly.Second, you need to demonstrate a 10% savings (5% for existing buildings) for your designed building compared with a baseline case meeting the minimum requirements of ASHRAE 90.1 (or Title 24-2005, Part 6 for California projects). You do this by creating a computer model following rules described in Appendix G of ASHRAE 90.1.Computer modeling offers the following key advantages:
- It can be used to provide feedback on your design both early on, and as the design progresses, so it’s best to use in this way rather than simply demonstrating compliance.
- It can help your team focus on the most cost-effective efficiency strategies, by plugging in different options and seeing the results.
- If your building is unconventional or complex in design, an energy model is the best way to account for that.
Your building type may not have a choice—you may have to follow this path, because both Options 2 and 3 are prescriptive compliance paths that are only available to specific building types and sizes.
However, if your building type and size allow, and you don’t want to embark on the complex process of computer modeling, which also requires expert assistance from a modeler or from a member of the mechanical engineer’s team, the prescriptive compliance paths are a good way to earn the prerequisite simply by following a checklist.
Passive design strategies such as shading to reduce solar heat gain are the most cost-effective ways to improve energy performance.Note, however, that when you get to EAc1, there are a lot fewer points on the table for the prescriptive paths, and that you have to follow each prescriptive requirement. These paths also require more collaboration and focus early on in design than you might think. The design team must work together to integrate all of the prescriptive requirements, and Option 3 even requires documentation of certain design processes.Option 2: ASHRAE Advanced Energy Design Guides
The Advanced Energy Design Guides are published by ASHRAE for office, warehouse, and retail projects less than 20,000 ft2—so if you don’t fall into one of those categories, you’re not eligible for this path.
These guides outline strategies to reduce energy use by 30% from 2001 levels, or an amount equivalent to approximately 10%–14% reduction from ASHRAE 90.1-2007. If you choose this compliance path, become familiar with the list of prescriptive requirements and commit to meeting all of them.
Option 3: Advanced Buildings Core Performance Guide
The Core Performance Guide path is a good option if all of the following are true:
- your project is smaller than 100,000 ft2,
- you cannot pursue Option 2 because there is not an ASHRAE guide for the building type,
- your project is not a healthcare facility, lab, or warehouse,
- and you would rather not commit to the energy modeling required for Option 1.
Comply with all requirements within Sections 1 and 2 of the guide. If you choose this path, become familiar with the list of prescriptive requirements and commit to meeting them. Also note that it’s not just a list of prescriptive requirements, but a prescribed process for achieving energy efficiency goals. You must demonstrate that you considered a couple of alternate designs, for example, and that certain team meetings were held.
Reduce energy loads first
Energy efficiency offers a clear combination of environmental benefit and benefit to the owner through reduced operational expenses, and potentially reduced first costs, if you’re able to reduce the size and complexity of your HVAC system with a more efficient envelope.
High-tech HVAC systems, and onsite renewable energy generation are often signature components of green buildings, but consider these strategies more “icing” on the cake, rather than a place to start. Start with building orientation and passive design features first. Also look at envelope design, such as energy-efficient windows, walls and roof, before looking at HVAC and plug loads. A poorly designed envelope with a high-tech HVAC system is not, on the whole, efficient or cost-effective.
District energy systems
Projects connected to district energy systems will not be able to utilize the system efficiencies of the base plant to demonstrate compliance with the prerequisite. They can plan on benefiting from these systems under EAc1, however.
Look for incentives
Focusing on energy efficiency and renewable energy generation can seem to add costs to a project, but there are a variety of utility-provided, as well as state, and federal incentives available to offset those premiums. (See Resources.)
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FAQs for EAp2
Is it acceptable to model a split-type AC with inverter technology compressor as a heat pump, like modeling VRF?
Ideally if the software you are using cannot model a technology directly then seek a published workaround related to your software. If you can't find a published workaround then model it as you think it should be modeled and explain how you have modeled it in the preliminary LEED submission.
A portion of our building envelope is historic. Can we exclude it from our model?
No, not if it is part of the LEED project. However, there is an exemption for existing building envelopes in Appendix G that allow you to model the existing condition in the baseline so you do not pay a penalty.
For an existing building, do I need to rotate the model?
No, not for an existing building.
Our project has a large process load—75%. Despite our efforts to make an efficient HVAC design, the cost savings are minimal. What can we do to earn this prerequisite and be eligible for LEED certification? Is there any flexibility in how we model the process load?
You must model accurately. Since you don't have enough savings in the building energy, find savings in the process. Either you will be able to demonstrate that compared to a conventional baseline the process being installed into the factory is demonstrably better than "similar newly constructed facilities," allowing you to claim some savings, or the owner needs to install some energy-saving measures into the process to get the project the rest of the way there. Either option can be difficult, but not impossible.
Account for process load reductions through the exceptional calculation method. A baseline must be established based on standard practice for the process in your location. Any claim of energy savings needs a thorough narrative explaining the baseline and the strategy for energy savings along with an explanation of how the savings were calculated.
Our process load is higher than 25%. Do we have to justify that?
It is common to have a 80%–90% process load in a manufacturing facility. The 25% default in LEED is based on office buildings. If you think your load is lower than 25%, it is recommended that you explain why in a short narrative. It is also recommended to briefly explain it if your load is 25% exactly, since that level commonly reveals that the process loads were not accurately represented.
Do the required savings for this prerequisite (and credit) need to come only from building energy, or also process loads?
The energy savings are based on the whole building energy use—building and process. LEED does not stipulate exactly where they come from.
Our local code references ASHRAE 90.1-2010. Should I use that for my documentation, or 90.1-2007?
For LEED 2009 you'll need touse 90.1-2007. There were some significant changes in 90.1-2010—too many to account for in your LEED review, and your project would also have a much harder time demonstrating the same percentage energy savings.
Our project doesn't have enough energy savings to earn the prerequisite. Can we get there by incorporating onsite renewables?
Yes according to LEED, although it is not recommended as a best practice, and it is usually more cost-effective to invest in energy savings in the building.
Can I claim exterior lighting savings for canopy lighting even though a baseline model cannot include shading elements?
You can assume exterior lighting savings for canopies against the baseline, but not the shading effects of canopies.
The project is built on a site with existing exterior lighting installed. How should this be accounted for?
If exterior lighting is present on the project site, consider it as a constant in both energy model cases.
Can mezzanines open to floors below be excluded from the energy model?
Any conditioned area must be included in the energy model.
How do I provide a zip code for an international location?
The Energy Star portion of the form does not apply to international projects.
For a project outside the U.S., how do I determine the climate zone?
Use the tables and definitions provided in 90.1 Appendix B to determine an equivalent ASHRAE climate zone.
For a project outside the U.S., how do I determine the Target Finder score?
International projects are not required to enter a Target Finder score. Target Finder is based on U.S. energy use data.
Do hotel rooms need automatic light shut-off control?
For Section 9.4.1.1c, a manual control device would be sufficient to comply with mandatory provisions.
How commonly are the 90.1 mandatory compliance forms submitted as part of EAp2/EAc1?
Submitting these forms is not common; however, it can be beneficial if you are applying for any exceptions.
The Section 9 space-by-space method does not include residential space types. What should I use?
Use the building area method.
Can the Passive House Planning Package (PHPP) be used to energy model for LEED?
Although there is no formal list of approved simulation tools, there are a few requirements per G2.2.1, including the ability of the program to provide hourly simulation for 8760 hours per year, and model ten or more thermal zones, which PHPP does not meet.
Can the Trace 700 'LEED Energy Performance Summary Report' by uploaded to LEED Online in lieu of the Section 1.4 tables spreadsheet?
The automated Trace 700 report provides less information than is requested by the Section 1.4 tables spreadsheet. The Section 1.4 tables spreadsheet must be completed.
Which baseline HVAC system do I use if my building has no heating or air conditioning?
Assign HVAC systems as per Appendix-G and Section 6 but set thermostatic setpointsSetpoints are normal operating ranges for building systems and indoor environmental quality. When the building systems are outside of their normal operating range, action is taken by the building operator or automation system. out of range so that systems never turn on.
Our project has a diesel backup generator. Should we include it in our energy model?
If it is only used for backup and not for regular use such as peak shaving—no.
Can SHGC be higher in the proposed than in the baseline model?
SHGC is not a mandatory provision so it is available for trade-off and can be higher than the baseline.
Do I need to justify the electrical and fuel rates I am using in my model?
You generally wouldn't need to upload any documentation, but particularly for a non-U.S. project, it may help to provide a short narrative about what they are based on.
Legend
- Best Practices
- Gotcha
- Action Steps
- Cost Tip
Pre-Design
Expand All
Indirect sunlight delievered through clerestories like this helps reduce lighting loads as well as cooling loads. Photo – YRG Sustainability, Project – Cooper Union, New York A poorly designed envelope with a high-tech HVAC system is not, on the whole, efficient or cost-effective. Start with building orientation and passive design features first when looking for energy efficiency. Also look at envelope design, such as energy-efficient windows, walls and roof, before looking at HVAC and plug loads. HVAC may also be a good place to improve performance with more efficient equipment, but first reducing loads with smaller equipment can lead to even greater operational and upfront savings. A poorly designed envelope with a high-tech HVAC system is not, on the whole, efficient or cost-effective. 
Use a preliminary energy use breakdown like this one to identify target areas for energy savings.Perform preliminary energy modeling in advance of the schematic design phase kick-off meeting or design charrette. The energy use breakdown can help identify targets for energy savings and point toward possible alternatives.
USGBC
Excerpted from LEED 2009 for New Construction and Major Renovations
EA Prerequisite 2: Minimum energy performance
Required
Intent
To establish the minimum level of energy efficiency for the proposed building and systems to reduce environmental and economic impacts associated with excessive energy use.
Requirements
Option 1. Whole building energy simulation
Demonstrate a 10% improvement in the proposed building performance rating for new buildings, or a 5% improvement in the proposed building performance rating for major renovations to existing buildings, compared with the baseline building performanceBaseline building performance is the annual energy cost for a building design, used as a baseline for comparison with above-standard design. rating.
Calculate the baseline building performance rating according to the building performance rating method in Appendix G of ANSI/ASHRAE/IESNA Standard 90.1-2007 (with errata but without addenda1) using a computer simulation model for the whole building project. Projects outside the U.S. may use a USGBC approved equivalent standard2.
Appendix G of Standard 90.1-2007 requires that the energy analysis done for the building performance rating method include all energy costs associated with the building project. To achieve points using this credit, the proposed design must meet the following criteria:
- Comply with the mandatory provisions (Sections 5.4, 6.4, 7.4, 8.4, 9.4 and 10.4) in Standard 90.1-2007 (with errata but without addenda1) or USGBC approved equivalent.
- Inclusion of all the energy costs within and associated with the building project.
- Compare against a baseline building that complies with Appendix G of Standard 90.1-2007 (with errata but without addenda1) or USGBC approved equivalent. The default process energy cost is 25% of the total energy cost for the baseline building. If the building’s process energy cost is less than 25% of the baseline building energy cost, the LEED submittal must include documentation substantiating that process energy inputs are appropriate.
For the purpose of this analysis, process energy is considered to include, but is not limited to, office and general miscellaneous equipment, computers, elevators and escalators,kitchen cooking and refrigeration, laundry washing and drying, lighting exempt from the lighting power allowance (e.g., lighting integral to medical equipment) and other (e.g., waterfall pumps).
Regulated (non-process) energy includes lighting (for the interior, parking garage, surface parking, façade, or building grounds, etc. except as noted above), heating, ventilation and air conditioning (HVAC) (for space heating, space cooling, fans, pumps, toilet exhaust, parking garage ventilation, kitchen hood exhaust, etc.), and service water heating for domestic or space heating purposes.
Process loads must be identical for both the baseline building performance rating and the proposed building performance rating. However, project teams may follow the exceptional calculation method (ANSI/ASHRAE/IESNA Standard 90.1-2007 G2.5) or USGBC approved equivalent to document measures that reduce process loads. Documentation of process load energy savings must include a list of the assumptions made for both the base and the proposed design, and theoretical or empirical information supporting these assumptions.
Projects in California may use Title 24-2005, Part 6 in place of ANSI/ASHRAE/IESNA Standard 90.1-2007 for Option 1.
OR
Option 2. Prescriptive compliance path: ASHRAE Advanced Energy Design Guide
Comply with the prescriptive measures of the ASHRAE Advanced Energy Design Guide appropriate to the project scope, outlined below. Project teams must comply with all applicable criteria as established in the Advanced Energy Design Guide for the climate zoneOne of five climatically distinct areas, defined by long-term weather conditions which affect the heating and cooling loads in buildings. The zones were determined according to the 45-year average (1931-1975) of the annual heating and cooling degree-days (base 65 degrees Fahrenheit). An individual building was assigned to a climate zone according to the 45-year average annual degree-days for its National Oceanic and Atmospheric Administration (NOAA) Division. in which the building is located. Projects outside the U.S. may use ASHRAE/ASHRAE/IESNA Standard 90.1-2007 Appendices B and D to determine the appropriate climate zone.
Path 1. ASHRAE Advanced Energy Design Guide for Small Office Buildings 2004
The building must meet the following requirements:
- Less than 20,000 square feet (1,800 square meters).
- Office occupancy.
Path 2. ASHRAE Advanced Energy Design Guide for Small Retail Buildings 2006
The building must meet the following requirements:
- Less than 20,000 square feet (1,800 square meters).
- Retail occupancy.
Path 3. ASHRAE Advanced Energy Design Guide for Small Warehouses and Self Storage Buildings 2008
The building must meet the following requirements:
- Less than 50,000 square feet (4,600 square meters).
- Warehouse or self-storage occupancy.
OR
Option 3. Prescriptive compliance path: Advanced Buildings™ Core Performance™ Guide
Comply with the prescriptive measures identified in the Advanced Buildings™ Core Performance™ Guide developed by the New Buildings Institute. The building must meet the following requirements:
- Less than 100,000 square feet (9,300 square meters).
- Comply with Section 1: Design Process Strategies, and Section 2: Core Performance Requirements.
- Health care, warehouse and laboratory projects are ineligible for this path.
Projects outside the U.S. may use ASHRAE/ASHRAE/IESNA Standard 90.1-2007 Appendices B and D to determine the appropriate climate zone.
1Project teams wishing to use ASHRAE approved addenda for the purposes of this prerequisite may do so at their discretion. Addenda must be applied consistently across all LEED credits.
2 Projects outside the U.S. may use an alternative standard to ANSI/ASHRAE/IESNA Standard 90.1-2007 if it is approved by USGBC as an equivalent standard using the process located at www.usgbc.org/leedisglobal
Potential Technologies & Strategies
Design the building envelope and systems to meet baseline requirements. Use a computer simulation model to assess the energy performance and identify the most cost-effective energy efficiency measures. Quantify energy performance compared with a baseline building.
If local code has demonstrated quantitative and textual equivalence following, at a minimum, the U.S. Department of Energy (DOE) standard process for commercial energy code determination, then the results of that analysis may be used to correlate local code performance with ANSI/ASHRAE/IESNA Standard 90.1-2007. Details on the DOE process for commercial energy code determination can be found at http://www.energycodes.gov/implement/
determinations_com.stm.FOOTNOTES
1 Project teams wishing to use ASHRAE approved addenda for the purposes of this prerequisite may do so at their discretion. Addenda must be applied consistently across all LEED credits.
2 Projects outside the U.S. may use an alternative standard to ANSI/ASHRAE/IESNA Standard 90.1‐2007 if it is approved by USGBC as an equivalent standard using the process located at www.usgbc.org/leedisglobal
Organizations
Database of State Incentives for Renewables and Efficiency (DSIRE)
This database shows state-by-state incentives for energy efficiency, renewable energy, and other green building measures. Included in this database are incentives on demand control ventilation, ERVs, and HRVs.
New York State Energy Research and Development Authority (NYSERDA)
Useful web resource with information on local/regional incentives for energy-efficiency programs.
American Council for an Energy-Efficient Economy
ACEEE is a nonprofit organization dedicated to advancing energy efficiency through technical and policy assessments; advising policymakers and program managers; collaborating with businesses, public interest groups, and other organizations; and providing education and outreach through conferences, workshops, and publications.
New Buildings Institute
The New Buildings Institute is a nonprofit, public-benefits corporation dedicated to making buildings better for people and the environment. Its mission is to promote energy efficiency in buildings through technology research, guidelines, and codes.
U.S. Department of Energy, Building Energy Codes Program
The Building Energy Codes program provides comprehensive resources for states and code users, including news, compliance software, code comparisons, and the Status of State Energy Codes database. The database includes state energy contacts, code status, code history, DOE grants awarded, and construction data. The program is also updating the COMcheck-EZ compliance tool to include ANSI/ASHRAE/IESNA 90.1–2007. This compliance tool includes the prescriptive path and trade-off compliance methods. The software generates appropriate compliance forms as well.
Rensselaer Polytechnic Institute: Daylighting Resources
Research center at RPI provides access to a wide range of daylighting resources, case studies, design tools, reports, publications and more.
IBPSA
International association of energy modelers with various national and local chapters.
Architecture 2030
Non-profit organization aiming at design community to increase collaboration for designing energy efficient buildings.
Low Impact Hydropower Institute
The Low Impact Hydropower Institute is a non-profit organization and certification body that establishes criteria against which to judge the environmental impacts of hydropower projects in the United States.
U.S. Department of Energy Building Technologies Program
The Building Technologies Program (BTP) provides resources for commercial and residential building components, energy modeling tools, building energy codes, and appliance standards including the Buildings Energy Data Book, High Performance Buildings Database and Software Tools Directory.
Web Tools
Energy Analysis Tools
This website discusses the step-by-step process for energy modeling.
Advanced Buildings Technologies and Practices
This online resource, supported by Natural Resources Canada, presents energy-efficient technologies, strategies for commercial buildings, and pertinent case studies.
U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy
This website is a comprehensive resource for U.S. Department of Energy information on energy efficiency and renewable energy and provides access to energy links and downloadable documents.
U.S. EPA, Combined Heat and Power Partnership
Information on cogenerationThe simultaneous production of electric and thermal energy in on-site, distributed energy systems; typically, waste heat from the electricity generation process is recovered and used to heat, cool, or dehumidify building space. Neither generation of electricity without use of the byproduct heat, nor waste-heat recovery from processes other than electricity generation is included in the definition of cogeneration., also called combined heat and power, is available from EPA through the CHPCombined heat and power (CHP), or cogeneration, generates both electrical power and thermal energy from a single fuel source. Partnership. The CHP Partnership is a voluntary program seeking to reduce the environmental impact of power generation by promoting the use of CHP. The Partnership works closely with energy users, the CHP industry, state and local governments, and other clean energy stakeholders to facilitate the development of new projects and to promote their environmental and economic benefits.
Advanced Energy Design Guides
Free download of AHSRAE energy savings guide, use for Option 2.
Lawrence Berkeley Lab: Building Technologies Department
Research warehouse for strategies and case studies of energy efficiency in buildings.
Efficient Windows Collaborative
An online window selection tool with performance characteristics.
Whole Building Design Guide (WBDG)
This website lays out design process for developing an energy efficient building.
AIA Sustainability 2030 Toolkit
This website discusses ways to improve design for lower energy demand as they relate to the AIA 2030 challenge.
Windows for High-Performance Commercial Buildings
This website includes discussion of design issues, materials and assemblies, window design decisions and case studies.
California Integrated Waste Management Board: Environmental and Economic Assessment Tools
This site lists multiple web-based and downloadable tools that can be used for energy analyses.
DEER: Database for Energy Efficient Resource
This database is maintainted by the California Energy Commission and lists resources related to energy use and efficiency.
Energy Design Resources - CA
Energy design tools are available to be used for free online or available to download.
Building Materials Property Table
This website lists performance characteristics for various envelope materials.
One Building
This is an online forum of discussion for energy efficiency, computer model software users.
EPA’s Target Finder
Target Finder is a goal-setting tool that informs your design team about their project’s energy performance as compared to a national database of projects compiled by the EPA.
Building Energy Software Tools Directory
This directory provides information on 406 building software tools for evaluating energy efficiency, renewable energy, and sustainability in buildings.
EnergyPlus Format Weather Data Resources
Weather data for more than 2100 locations are available in EnergyPlus weather format.
DOE-2 Format Weather Data Resources
Weather data for U.S. and Non-U.S. locations in BIN format.
BEMbook – Building Energy Modeling Book
A web-based, free content project by IBPSA-USA to develop an online compendium of the domain of Building Energy Modeling (BEM). The intention is to delineate a cohesive body of knowledge for building energy modeling.
Technical Guides
Advanced Buildings Core Performance Guide
A guide for achieving energy efficiency in new commercial buildings, referenced in the LEED energy credits.
ENERGY STAR Building Upgrade Manual
This manual is a strategic guide for planning and implementing energy-saving building upgrades. It provides general methods for reviewing and adjusting system control settings, plus procedures for testing and correcting calibration and operation of system components such as sensors, actuators, and controlled devices.
Treatment of District or Campus Thermal Energy in LEED V2 and LEED 2009 – Design & Construction
This document is USGBC’s second (v2.0) major release of guidance for district or campus thermal energy in LEED, and is a unified set of guidance comprising the following an update to the original Version 1.0 guidance released May 2008 for LEED v2.x and the initial release of formal guidance for LEED v2009.
COMNET Commercial Buildings Energy Modeling Guidelines and Procedures
This manual offers guidance to building energy modelers, ensuring technically rigorous and credible assessment of energy performance of commercial and multifamily residential buildings. It provides a streamlined process that can be used with various existing modeling software and systems, across a range of programs.
2009 ASHRAE Handbook of Fundamentals, Chapter 19
Chapter 19 is titled, “Energy Estimating and Modeling Methods”. The chapter discusses methods for estimating energy use for two purposes: modeling for building and HVAC system design and associated design optimization (forward modeling), and modeling energy use of existing buildings for establishing baselines and calculating retrofit savings (data-driven modeling).
Treatment of Distric or Campus Thermal Energy in LEED v2 and LEED 2009 (Updated August 13, 2010)
Required reference document for DES systems in LEED energy credits.
Publications
ANSI/ASHRAE/IESNA Standard 90.1–2007 User’s Manual (ASHRAE).
ASHRAE writes standards for the purpose of establishing consensus for: 1) methods of test for use in commerce and 2) performance criteria for use as facilitators with which to guide the industry.
Energy Information Administration
Energy statistics from the U.S. government.
New Buildings Institute— Advanced Lighting Guidelines: 2003 Edition
This guide includes instructional graphics and superior lighting design solutions for varying types of buildings and spaces, from private offices to big box retail stores.
Building Energy Performance News
This website offers information on energy efficiency in buildings, highlighting success stories, breakthrough technology, and policy updates.
GreenSource magazine
Bimonthly publication on case studies and new technologies for energy efficiency in commercial buildings.
AIA Local Leaders in Sustainability: Green Incentives
AIA publication highlighting local and state green building incentives.
Federal Research and Devlopment Agenda for Net-Zero Energy, High-Performance Green Buildings
2008 guidelines and performance goals from the National Science and Technology Council.
Energy Design Resources (EDR) Simulation Guidebooks
Information about energy-efficient building practices available in EDR's Design Briefs, Design Guidelines, Case Studies, and Technology Overviews.
Software Tools
Building Energy Software Tools Directory
DOE tools for whole building analyses, including energy simulation, load calculation, renewable energy, retrofit analysis and green buildings tools.
Building and Fire Research Laboratory
This is a computer program that predicts the one-dimensional transfer of heat and moisture.
DesignBuilder and EnergyPlus
DesignBuilder is a Graphical User Interface to EnergyPlus. DesignBuilder is a complete 3-D graphical design modeling and energy use simulation program providing information on building energy consumption, CO2Carbon dioxide emissions, occupant comfort, daylighting effects, ASHRAE 90.1 and LEED compliance, and more.
Integrated Environmental Solutions – Virtual Environment Pro / Apache
IES VE Pro is an integrated computing environment encompassing a wide range of tasks in building design including model building, energy/carbon, solar, light, HVAC, climate, airflow, value/cost and egress.
Advanced Energy Design Guide Checklist
Option 2: Prescriptive Compliance Path
Use this checklist of prescriptive requirements (with sample filled out) to have an at-a-glance picture of AEDG requirements for Option 2, and how your project is meeting them.
Advanced Buildings Core Performance Guide (CPG) Checklist
Option 3
This spreadsheet lists all the requirements for meeting EAp2 – Option 3 and and EAc1 – Option 3. You can review the requirements, assign responsible parties and track status of each requirement through design and construction.
Energy Simulation Narrative
Option 1
Sometimes the energy simulation software being used to demonstrate compliance with Option 1 doesn't allow you to simulate key aspects of the design. In this situation you'll need to write a short sample narrative, as in these examples, describing the situation and how it was handled.
Equipment and Product Cut Sheets
All Options
In your supporting documentation, include spec sheets of equipment described in the Option 1 energy model or Options 2–3 prescriptive paths.
PRM Table
Option 1
This is a sample building energy performance and cost summary using the Performance Rating Method (PRM). Electricity and natural gas use should be broken down by end uses including space heating, space cooling, lights, task lights, ventilation fans, pumps, and domestic hot water, at the least.
Samples
Tariff Charges
Option 1
Option 1 calculates savings in annual energy cost, but utility prices may vary over the course of a year. This sample demonstrates how to document varying electricity tariffs.
Samples
Modeled Energy Reductions
Option 1
This graph, for an office building design, shows how five overall strategies were implemented to realize energy savings of 30% below an ASHRAE baseline. (From modeling conducted by Synergy Engineering, PLLC.)
U.S. Climate Zones
All Options
The climate zones shown on this Department of Energy map are relevant to all options for this credit.
Tools
Appendix G Fan Power Calculator
Option 1
This spreadsheet, provided here by 7group, can be used to calculate the fan volume and fan power for Appendix G models submitted for EAp2/EAc1. Tabs are included to cover both ASHRAE 90.1-2004 and 90.1-2007 Appendix G methodologies.
LEED Online Forms: NC-2009 EA
The following links take you to the public, informational versions of the dynamic LEED Online forms for each NC-2009 EA credit. You'll need to fill out the live versions of these forms on LEED Online for each credit you hope to earn.
Version 4 forms (newest):
- EAp1: Fundamental Commissioning
- EAp2: Minimum Energy Peformance
- EAp3: Fundamental Refrigerant Management
- EAc2: On-Site Renewable Energy
- EAc4: Enhanced Refrigerant Management
- EAc5: Measurement & Verification
Version 3 forms:
- EAp1: Fundamental Commissioning
- EAp2: Minimum Energy Peformance
- EAp3: Fundamental Refrigerant Management
- EAc1: Optimize Energy Performance
- EAc2: On-Site Renewable Energy
- EAc3: Enhanced Commissioning
- EAc4: Enhanced Refrigerant Management
- EAc5: Measurement & Verification
- EAc6: Green Power
These links are posted by LEEDuser with USGBC's permission. USGBC has certain usage restrictsions for these forms; for more information, visit LEED Online and click "Sample Forms Download."
Design Submittal
Documentation for this credit can be part of a Design Phase submittal.
LEEDuser is produced by BuildingGreen, Inc., with YR&G authoring most of the original content. LEEDuser enjoys ongoing collaboration with USGBC.
1422 Comments
Proposed v Baseline Outdoor air
I am working on a multifamily building. The proposed system is a Rooftop unit with constant vlume and 100% outdoor air. No return or exhaust and a set SA CFM.
My question is whether in this case, since the supply air and the ventilation CFM are equal; I should model the baseline supply air CFM with the calculated CFM, based on the 20 degree delta T, or using the same SA CFM as in the proposed building.
Please reply
Thanks
The baseline needs to follow the Appendix G rules. So it is a system 1 or 2 and it needs to be auto-sized by the software according to G3.1.2.8.
Light Scheduling
1) Assume the same scheduling is used in both design and baseline case, may I schedule lights to be off during occupied hours in a zone (both baseline and design models)?
2) Taking this a step further, can I model a control (in both baseline and designcase) that will mimick occupant behaviour to turn off lighting when a target luxMeasurement of lumens per square meter. level has been reached in the zone?
1) Schedule the lighting based on the expected occupancy pattern. If the lights in a certain area would normally be off then schedule it that way.
2) I assume you are talking about a control that responds to daylight. If so this is a viable control strategy and you can claim savings. So the "schedule" does not have to be identical if that is the only way you can model the savings (do an exceptional calculation). In many energy modeling software you can model such a control directly (keeping the schedules the same and avoiding the exceptional calculation).
I am purposefully trying NOT to take "credit" for switching the lighting off, because I have no "automated" control. I would make use of the lighting level control functionality of energyplus to model user behaviour to switch the lights off when my near passive house zone is receiving many thousands of watts of direct solar radiation to avoid the useless extra light from the electric light and save some energy and avoid overheating this solar sensitive space.
Theoretically schedules are free to define as long as they are the same for the baseline, right? But is automated control used to model user behaviour (the same control in both baseline and design) allowed?
Take it a step further and apply the same logic to blinds that are user operated, or windows that are opened for natural ventilation.
I think you are getting my question...
Always helpful to understand the motivation behind the questions!
Technically you are correct about the schedules and manual controls. Table G3.1 does indicate that the schedules must be typical and are subject to approval by the rating authority (GBCI). The reality is that schedules are typically not submitted or reviewed for LEED so no one would likely question it. Using automated control (a schedule) to simulate user behavior is technically not allowed but since you are keeping the schedules the same it would likely be acceptable.
One could certainly argue that you are modeling the building as accurately as you can. So if there is a conflict with the "rules" I tend to vote for the accuracy.
Thanks Marcus. I hate being an experimental rat, but in this particular case, I may need to.
A related question...if it turns out that my naturally ventilated building with radiant floor heating manages to get under 300 hours for the heating loads not met hours (assuming the cooling setpoint is set to some high setpoint so as to not turn on and I'm just concerned with heating load not met hours), it is more than likely that the unmet load hours from the baseline case is much less than that of my designcase model, simply because heating with air is much faster response time wise than radiant surface heating, i.e. the differential is very likely to exceed the required 50 hours.
May it be valid to decrease the heating sizing parameter of the baseline case to something less than 1.25, to increase the unmet load hours until they are within 50 of the designcase model?
I know this stuff is not exactly in the standard. Just like to hear your opinion.
You are allowed to do so based on G3.1.2.2. Make sure you have tried everything else first before reducing baseline capacities as this should be your last resort to get the unmet load hours in alignment. I reviewed a project recently where the capacities were reduced well under 100% and it calls into question the accuracy of the proposed design.
Awesome! Downward adjustment...who would have thought. Of course, your worries are the same as mine. Thanks for sharing your experience, Marcus. This means so much to the community of struggling young engineers.
ASHRAE Mandatory provisions 10.4
Hello,
I’m currently working on a LEED NCv2009 project located in Spain. My question is about the compliance of the section 10.4.1 (Electric Motors) of ASHRAE 90.1-2007. Should an European building comply with the requirements of the Energy Policy Act of 1992?
Thank you very much.
Best regards,
Electric motors must meet the requirements in the efficiency table regardless of the location of the project. Keep in mind that there a various exemptions from the efficiency requirements for electric motors. They must be base mounted, single speed, 3 phase, etc..
I Thought I have seen somewhere that the equivalence with the energy Policy Act is that the motors should be at least IE2 class.
Baseline system types and building area
We have the project of to 250,000 sq ft. The Air conditioned area is only 50,000 sq.ft. The rest is enclosed unconditioned area (No HVAC) of 200,000 sq.ft. What area should we use to determined the baseline system 1-8. it seems unfare to use 250,000 sq.ft.
Thanks
Use the area of the conditioned space.
Exceptional Calculations
I have a new bubilding which will be mostly a performing arts theater and school gymnasium. Because these two spaces make up well over half of the building, my annual proccess energy costs are not greater than or equal to 25% of the total energy costs for the proposed design. In fact they are only 9%. Do I need to use an exceptional calculation or can I write a narrative explaining that the type of building I have would never have the amount of process loads needed to achieve the 25%?
If I need to us an exceptional calculation does anyone have any suggestions of how to accomplish this?
Not all projects will have at least 25% process loads; that number is simply representative of a "typical" amount. If your project has less, indicate through a narrative why that is so. Exceptional Calculation Methods are for claiming savings from the process loads, and are necessary when the percent process load differs between the baseline and proposed models.
Central Plant providing energy to more than one buildings
Hi,
We have a project where the Central Plant, consisting of a geothermal heat exchanger, is considered to provide energy to more buildings than the building seeking LEED certification.
Could this be considered as a building using purchased heating and cooling from a district energy system and therefore to be handled according to Addenda ai?
I don't think so. Your situation is not really purchased heating or cooling. Neither hot water, nor chilled water is used in the system, it is a heat exchanger.
Thanks for the answer. How should we consider this system in that case? Do we need to take into consideration the other buildings which are using this heat exchanger to the total efficiency of the Central Plant?
I think you would just model the portion of the well field associated with the project in question.
Selecting baseline for mixed use building
We are working on a project which is mixed use facility (6 storey/G+5) . The first & 2nd floor is used for office & remaining for residential.
Please guide how to select baseline HVAC system as per ASHRAE 90.1.
The residential is System 1 or 2. For the office see if G3.1.1 Exception a applies. If so then enter Table G3.1.1A with the office area and fuel type and select the system type. If not the whole building is system 1 or 2.
purchased heat pumps for ASHRAE 90.1
Dear Group,
As you know additional requirements from LEED led to purchased heat water coils being substituted for furnis heat coils in some unitary systems. 90.1-2007 therefore had requirements for the hot water pumps only for systems that normaly have hot water, such as 1, 5 and 7.
Consider that I am using 90.1-2007, but have purchased heat...as there is no pump requirement, should I
1) use that of 90.1-2010
2) use the proposed case pump power and scale the rated pressure rise acordingly with the baseline auto-sized flowrates and the required motor efficiency.
I vote for 2) as I'm using 2007 consistantly. I tested it with the 2010 requirement and the pump power would decrease by about 20%.
Kind regards,
Jean.
We vote for 2 as well. The baseline W/GPM should be identical to the proposed.
Major Renovation vs. New Construction
We are working on a library project that involves the renovation of an existing facility, and the addition of a new wing. Both are included in the LEED scope of work, and all existing mechanical equipment will be replaced as part of the project. (The addition will double the size of the existing building)
I initially labelled the project as "Major Renovation" and indicated the amount of "Addition Floor Area" assuming the excel template would pro-rate the EAp2 credits achieved. However, when I change the addition floor area there appears to be no change in credits awarded. Does this mean the template is calculating points based solely on the "Major Renovation" requirements alone? Our energy modeller wants to provide his own excel sheet that will pro-rate the credits based on square footage of new, and square footage of existing, but this means our LEED document will not accuretely represent total credits achieved.
Any thoughts on how best to approach this?
(This is based on the CaGBC's version of NC2009 - my apologies if there is any difference w/ USGBC)
Not sure about the Canadian system but the form in the US system automatically calculates the proper percentage based on the ratio of new and existing.
Ventilation requirements for naturally ventilated spaces
A difficalt case: Radiant floor + Nat Vent
LEED increased ventilation credit requires that when using the macroscopic airflow simulation compliance path for naturally ventilated spaces:
1) 90% of the occupied spacesOccupied Spaces are defined as enclosed spaces that can accommodate human activities. Occupied spaces are further classified as regularly occupied or non-regularly occupied spaces based on the duration of the occupancy, individual or multi-occupant based on the quantity of occupants, and densely or non-densely occupied spaces based upon the concentration of occupants in the space. are prooven to be able to provide the required ventilation requirements as per the chosen standard (normally 62.1)
2) these ventilation requirements should also be consistantly applied to the energy model of EAp2 (note only occupied spaces are considered)
3) LEED has additional exhaust requirements for contaminated spaces (if IAQc5 is aimed for), which must also be considered by the increased ventilation credit and EAp2
Q) what ODA and or Exhaust requirements should be applied to the model in EAp2 to non- and regularly occupied spacesRegularly occupied spaces are areas where one or more individuals normally spend time (more than one hour per person per day on average) seated or standing as they work, study, or perform other focused activities inside a building. (that are spaces without harmfull contaminants)?
E.g. WC, kitchen. Typically, naturally ventilated WCs and kitchens won't be expected to have ACHThe number of times per hour a volume of air, equivalent to the volume of space, enters that space. quite as high as 62.1 or is mech exhaust required for those space type examples?
Q2) How does this tie in with the baseline system type required in the proposed case to provide the missing conditioning system (in this case cooling)?
Jean
Q3) how does Appx G handle system types and space ventilation rates for the baseline where in the proposed design there are only exhaust fans, but with hydronic heating?
Regarding natural ventilation - are you wanting to claim energy saving credit for a natural ventilation system or are you talking about the natural ventilation through operable windows in ASHRAE 62?
Q - Assuming the ASHRAE 62 type of nat vent, you basically model infiltration and no exhaust in most spaces. In the areas with harmful contaminants mechanical ventilation would be required by ASHRAE 62.
Q2 - Ventilation is separate in the baseline if it is separate in the design and you do not model one if you do not have one installed. I think that the requirement to add a system that does not exist in the proposed is just plain busywork. You can always get around it having an effect on your model by adjusting the temperature settings.
Q3 - The baseline system type is still from G3.1.1 and is not based on the proposed air or heating distribution systems. The space ventilation rates still need to be identical.
So are you saying that for a 62.1 Nat Vent compliant model, I should model ventilation rates as zero (oda requirements = zero) and only infiltration (infiltration is what happens when all windows/doors are closed, whereas Natural Ventilation is what happens when you open a window).
If you are saying (and I hope you are not) that I should model Natural Ventilation, then I would say that
1) this can only be believably done using CO2Carbon dioxide and temperature to anticipate user behaviour on a minute by minute bases and that wild temperature swings (especially in winter) will play havoc with unmetloadhours.
2) This model would have to incorporate when users close windows due to too high air change rates (and incorporate wind velocities).
3) The baseline building windows would have to be the same size to allow the same venting possibility, but may not vent the same or at the same time if using the same control algorithms. It would also require that only non-operable windows may be size adjusted to meet the 40% WWR.
How do I know this? Because I have tried on and off over the last 3 years to do this for an exceptional calculation methodology.
Section 6 of 62.1 says "This section is not required for natural ventilation systems;" This will also affect the exhaust requirements for WCs and Kitchens.
In the case of WCs, they WCs don't even need the 4% of net occupiable floor area for window opening area, as the net occupiable floor area is zero (it is not an occupiable space as per the definition in the standard).
It looks like I will be resetting all my ODA requirements to zero.
You said "In the areas with harmful contaminants mechanical ventilation would be required by ASHRAE 62." I don't think this is the case for a naturally ventilated space as they exclude section 6. Could you point me to the relavent section in 62.1 (I know this is a requirement of IAQc5, but I don't find it in 62.1).
The mechanical ventilation rates would be zero if you do not have any mechanical ventilation in the design. You should model natural ventilation since it has an impact on the loads and it should be identical in both cases. You would only need to do the exceptional calculation if you are claiming savings related to natural ventilation.
1) do not schedule the windows to open when outdoor conditions would require the operation of the HVAC systems.
2) yes this would need to be scheduled
3) Good point. Make sure that the operable window area is identical.
That is what happens when you answer a question off the top of your head.
You are correct that 62.1 does not require mechanical ventilation for areas with harmful contaminants.
Our interpretation of occupiable space, based on the definition, would be that WCs are occupiable spaces and therefore require ventilation.
Thanks for your inputs, Marcus. Greatly appreaciated.
Radiant Floor Heating with Natural Ventilation
Hi Group, I have a project with only Radiant Floor Heating with Natural Ventilation. I have modeled both baseline and proposed with the baseline HVAC for cooling (the missing system). However, because of the large internal masses, the responsiveness of the radiant system is far slower than that of an air heating system such as in the baseline. This gives me 0 unmetloadhours for the baseline case, but 290 unmetloadhours for the proposed design case. Although I find the unmetloadhours in bounds at under 300, the differential with the baseline is more than 50. Increasing the capacity of the system has no effect, obviously...a radiant surface at max temp can only have a certain maximum heat transfer due to free convection limitations.
Q) is it therefore the "right" thing to do to include the heating system of the baseline to catch these small unmetloadhours? Or should I try and explain away the large deviation between designcase and baseline case for unmetloadhours for heating?
Jean
Hello Jean, I solved a similar problem working with the control of the radiant floor. It was something similar: during the night the setpoint temperature was 15°C and since the 9.00 the setpoint temperature was 20°C. The problem with the not met sepoint temperatures was during the morning, therefore I anticipated the “diurnal mode” of the heated floor in the last hours of the night (obviously without changing the zone setpoint temperature; the practical way to solve the problem depends on the used software).
Because of the thermal inertia of the heated floor I was able to anticipate the “night mode” in the afternoon.
Probably also increasing (in a reasonable way) the supply water temperature could help.
I don’t know if working with the control system could be useful in your case. Perhaps your problem depends on too high natural ventilation rates, even when there are very cold outdoor temperatures. In that case you should try changing the management of natural ventilation.
I think that the resolution of the problem depends a lot on the used software. Maybe a discussion in the maling list of EnergyPlus could be interesting :-)
Regards
It's a bit more complicated...the culprit rooms are rooms that require per ashrae have high exhaust rate requirements, like a kitchen or WC. The makeup air is currently comming from outside...perhaps the solution is to have the makeup air come from adjacent rooms and setting the AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition) 2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork. for these spaces to circulation only. I'll give it a go.
Actually, thermodynamically it makes little difference where the extra ODA is heated, and for the additional effort, I think I'll just include the 2nd system for now.
Just an update...as the real ODA requirement for my tested WC is zero, I have found that giving the system 3 cooling system a outdoor air requirement of zero, whilst simultaneously pulling the make up air of the required exhaust rate from the adjacent space seems to solve my problem.
Cooling EIR as the only evidence of PFan modeled separately?
We received an comment review about a system 6 (PVAV w/ PFP boxes) baseline model in eQuest: The SV-A reports indicates that the cooling efficiencies for the HVAC systems were not correctly reflected in the Baseline model and the supply fan energy has not been broken out as required (per G 3.1.2.1). We responded with a revised EIR (not eQuest Default calculation) and a narrative explaining the deduction steps. But it again was denied by the reviewer.
My question is, in the appealing, am I supposed to keep fixating on the EIR calculation, or is there any other evidence of fan power being broken out in the SV-A report that I neglected before? Many thanks
The EIR value is the only thing in the SV-A report that addresses the break out of fan power. Perhaps the issue is not using the eQUEST default calculation. So keep fixating.
Hot Water - 3 Fuel Sources - Baseline Model
Hi,
We are Energy modelling a project with 3 types of systems to heat water:
1.- Solar Collector
2.- Electrical Heat PumpA type of heating and/or cooling equipment that draws heat into a building from outside and, during the cooling season, ejects heat from the building to the outside. Heat pumps are vapor-compression refrigeration systems whose indoor/outdoor coils are used reversibly as condensers or evaporators, depending on the need for heating or cooling. In the 2003 CBECS, specific information was collected on whether the heat pump system was a packaged unit, residential-type split system, or individual room heat pump, and whether the heat pump was air source, ground source, or water source.
3.- Hot water Boiler - Gas
For the "BASELINE" model, should I model the Solar Collector?
or
Should I just consider it for the PROPOSED model because it´s going to reduce the energy consumption?
Thanks.
You would model a gas hot water heater in the baseline and you'd model the proposed as designed.
A slight amendment to Anthony's suggestion - model the baseline for the heat pumpA type of heating and/or cooling equipment that draws heat into a building from outside and, during the cooling season, ejects heat from the building to the outside. Heat pumps are vapor-compression refrigeration systems whose indoor/outdoor coils are used reversibly as condensers or evaporators, depending on the need for heating or cooling. In the 2003 CBECS, specific information was collected on whether the heat pump system was a packaged unit, residential-type split system, or individual room heat pump, and whether the heat pump was air source, ground source, or water source. as electric water heater and the baseline for the boiler as gas water heater.
The solar is all savings!
Anthony,
We had the same question as Fabiano's a few days ago and we found in ASHRAE 90.1-2007, Appendix G, 11-Service Hot-Water Systems that:
"The service hot-water system in the baseline building shall use the same energy source as the corresponding system in the proposed design..."
So we concluded we had to model the solar water heating system in the baseline. I'm confused now...
Solar hot water is considered "on-site renewable energy" and should be modeled in the proposed only, as it is a savings. Report the savings in the appropriate section in the EAp2 template. you should be good to go!
Thanks,
I am going considering the heat pumpA type of heating and/or cooling equipment that draws heat into a building from outside and, during the cooling season, ejects heat from the building to the outside. Heat pumps are vapor-compression refrigeration systems whose indoor/outdoor coils are used reversibly as condensers or evaporators, depending on the need for heating or cooling. In the 2003 CBECS, specific information was collected on whether the heat pump system was a packaged unit, residential-type split system, or individual room heat pump, and whether the heat pump was air source, ground source, or water source. (electrical) and the boiler (gas) for the baseline.
The solar will be the savings for the Proposed then.
I can't find any LEED Interpretations on the subject, but I've always handled DHWDomestic hot water (DHW) is water used for food preparation, cleaning and sanitation and personal hygiene, but not heating. systems similarly to HVAC system types. So for example, if the proposed building had a hybrid (gas/electric) HVAC system, you would use gas in the baseline. Similarly, if my proposed DHW system is a hybrid, I would use gas in the baseline. I agree that the user's manual doesn't really clarify this issue, so my guess is that either approach would be acceptable to GBCI.
The GBCI reviewer will follow the guidance in Table G3.1-11 Baseline that was quoted by Marcio above for the baseline service hot water (SHW) systems. "The service hot-water system in the baseline building shall use the same energy source as the corresponding system in the proposed design..." This language is pretty clear. SHW does not follow the same baseline guidance as the HVAC systems.
The solar hot water is addressed by the Exception to G2.4 which indicates that you use the back up source for the baseline when using an on-site renewable in the Proposed.
You're right, I started reading at bullet "a" which wasn't helpful.
No HVAC / Natural Ventilation - Unmet Hrs
Hello,
I am currently working on a LEED NCv2009 project which includes a small building ~1,150sf, and has 200sf of regularly occupied space. The remainder of the building is restroom and storage area. The entire building is naturally ventilated with permanent louvers (always open) located at the top of each wall all the way around the building. The regularly occupied area also complies with natural ventilation requirements of ASHRAE 62.1 via appropriately sized operable windows and the building is located within a block of the ocean in a temperate climate. We are running into difficulty achieving the 10% minimum energy cost savings required for EAp2 as there is little energy usage, aside from process, in the building without an HVAC system. We basically have interior and exterior lighting (façade and site), a hot water heater and receptacle. We are using EnergyPro and T-24.
Questions:
1) Since there is no heating or cooling, we do not have to model either. Correct? It is my understanding that if there was heating we would have to also model cooling or vice versa, however if the building is not conditioned we do not have to model either.
2) Do we have to provide any information for unmet heating and cooling hrs if we are not claiming savings for natural ventilation?
3) Any other general suggestions for modeling this scenario to achieve the requirements of EAp2??
Thanks!
According to Table G3.1.10 , you have to simulate, even if no cooling and heating system exist in building. In this case your baseline case and Proposed case HVAC system will be similar.
In your case if your building is residential than your baseline system will be System 2, if it is commercial than your baseline system will be system 4. For proposed case you have to use similar system that you have used for Baseline case.
Basic fundamental behind similar system is that you can show saving from envelop, lighting, HWH (if your envelop, interior lighting is more efficient than baseline) .
Hope this info helps you.
Good luck
Thanks Anil!
1. I am not sure of the T24 rules but it certainly makes sense to not model systems that do not exist and are identical. Even in 90.1 there is a work around to the requirement that Anil mentions - just change the temperature settings so the fake systems do not run.
2. No you do not.
3. Implement lighting and service hot water saving measures! Are you claiming any hot water demand reduction?
Thanks for the response Marcus!
1. We attempted to fake the systems with the temperature set points, however this apparently is not possible in EnergyPro. We ended up discussing this with EnergySoft who confirmed this would not be an option.
2. Thank you for confirming. This is good news.
3. I have a note to confirm that we are claiming hot water demand reduction, however am unsure right now. We are seeing some savings from the service hot water and may be able to capture some additional savings by switching to a more efficient unit. Lighting has been the Achilles heel for the project. From the beginning we were counting on efficient lighting to pull us through and achieve the minimum 10% savings, then the County requested additional lighting for safety measures and we are back to the drawing board with little room to work (without adding additional energy usage).
The standard is intended to regulate mainly conditioned spaces. IMO if the space is not conditioned, it has no "real" setpoint to meet. So the heating setpoint could be -50 deg C and the cooling setpoint could be +100 deg C. I have no problem with this for unconditioned spaces, unless they are regulary occupied...in which case I believe the intent of the standard is to anticepate that dissatisfied users will retrofit conditioning systems if they are often dissatisfied. For naturally ventilated spaces the upper bounds could be 28-32 deg C and the lower bounds at say 15 deg C. Check out AM10 to back up wild claims like this.
There are no envelope requirements for unconditioned spaces, meaning baseline = designcase. It's going to be hard to show enough savings.
Thank you Jean, I appreciate the suggestion to look at AM10. The project is located near the ocean in Southern California and the occupied portion is essentially a concession area which will serve the public at a park with a water fountain / feature. A majority of the time the weather in this area does fall between 15 and 32 deg C, and the concession area will likely not be open if it is below 15 deg C. There may be 2 times a year when the temperature is above 90 degrees F this close to the ocean.
I agree that it is going to be difficult to show enough savings as currently designed. We have discussed including AC in the building to take advantage of energy savings from the envelope and AC ...however it seems counterintuitive to include AC in a building to achieve energy savings for LEED. If we thought that thermal comfort was a real concern it would be a different story. I think that going back to the owner and discussing the lighting one more time may be appropriate, however I wanted to make sure that we would not run into problems with unmet hrs before asking for design changes. Alternatively, maybe looking into the thermal comfort and pursuing savings via exceptional calculations for natural ventilation is appropriate?
Re: via exceptional calculations for natural ventilation
In my experience, unless you have moterized automatic window/vent control to fractionally modulate the openings, regulating the temperature and or room air quality with windows/vents is very hard to proove with a simulation program.
I am currently attempting to do so (i.e. mimick building user behaviour for opening and closing windows) and it is very time intensive and shows pretty erratic behaviour. Especially in winter, due to cold outdoor temps, the room air temperature swings are huge. In 10 min the temp can drop from 22 degC to 17 deg C by opening windows when it is -2 outside. Wind plays a role, air speed plays a role, air quality plays a role.
This particular project has huge internal mass and internal gains, meaning even without heating, the zone overheats in winter if the windows remain closed. If you open a window the room overcools quickly, and as soon as you close the window, it overheats just as fast. I'm having to split the windows in each zone into 2 groups to "modulate" the total opening area (as windows have at most just 3 settings (closed, open, tip).
And I'm still testing and tuning...
If you go this route, good luck.
I suggest doing the baseline AC in both models (where none are planned).
Exterior Lighting for Baseline
We refer to ASHRAE 90.1 Supplementary Addendum i which discuss the LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. of tradable surface on table 9.4.5. In this table, they allow the base site light power in "watts" to be added for the given zones such as zone 2 of 600 watt. Since the allowed LPD of all areas of this addendum is very low. Can we add the 600 watt as the power of the baseline?
Do we even have to follow the addendum? Can we just follow the standard?
Thanks
You do not have to follow the addendum, they are all optional. Looks like the base site lighting power replaced the additional 5% allowance, so yes you can add it.
VAV FAN POWER BOX MODELING
I am working on a project where the base line hvac system is type 6 VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. with fan power boxes. ASHRAE 90.1 requires the fan power box CFM to be sized at 50% of the peak CFM at 0.3 W/CFM.
There is no guidance in 90.1 user manual on how to comply with this requirement, further more when we asked the modeling software help line they said that it can’t be done and that the software is automatically sizing the fan power box CFM at 50% of the system heating CFM not the cooling CFM.
This comment keeps coming almost on every project with this type of system. Any input on how to deal with this issue?
What software are you using?
trace 700
I am also creating baseline with system-6. For system i have selected FP VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. with reheat, than for FP vav box, I took 50 % of Total CFM (Cooling) and multiply 50 % of CFM by 0.3 to get wattage. And input total wattage into secondary supply fan in Fan tab.
After reading above comment it sounds like, it is more complicated than what i did.
Any suggestion?
Thank you
Just to be clear the value is 0.35 W/cfm.
We are not aware of any limitations in Trace for accurately modeling this issue. Anil's approach sounds right to us but we are not Trace experts. Consult the help desk again or post your issue on the Trace users group at onebuilding.org. Any other thoughts?
thanks Marcus and Anil that's easy way of doing it.
Outdoor Pool
Hey,
I have a Multi-Story Office building that is looking to achieve 19 points by purchasing PV Panels to offset the energy consumption. The initial study did not included a outdoor pool, which is inside the LPB. The pool and it's equipment are outside of the building. We are contemplating using a Dedicated Heat Recovery Chiller in the building to heat the outdoor pool. Must I include the pool heating as a process load or can I do an exceptional calculation outside the model and modify the DHRC COP to account for the efficiency improvements? The PV array has already been bid on, so including the pool load in the Energy Model will reduce the effectiveness of the PV Array.
Thanks!
You must include the pool. Check to see if some components of the pool heating are regulated by 90.1 in Section 7. If it is then it is not process. How you model it depends on the capabilities of the software you are using.
Envelope test
In a multiple building project we have 100 identical staff housing units that need to comply with AHRAE for EAP2. Must we test each and every building and can we do a % of them?
If they are truly identical, including orientation,etc. then you would only have to do one. Are they all part of one LEED project? Are you looking a the LEED Volume Program?
Wood Chip Boiler base case?
This is a question from a non-energy modeler looking for some guidance on base case vs. design case for a LEED energy model that a consultant is working on. The project is a school. Energy sources for the project are biofuel (wood chip) boiler and some geothermal. What should the base case fuel source be for the LEED energy model? Wood chips are cheap compared to heating oil, so we are seeing huge energy cost savings in the energy model if oil is the base case. EAc1 is indicating near 19 points. Could this be correct? It is an energy efficient project but 19 points seems high to me so I am wondering if we chose the base case correctly.
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