Michael I. Rosenberg

U.S. Department of Energy commercial reference building models of the national building stock

The U.S. Department of Energy (DOE) Building Technologies Program has set the aggressive goal of producing marketable net-zero energy buildings by 2025. This goal will require collaboration between the DOE laboratories and the building industry. We developed standard or reference energy models for the most common commercial buildings to serve as starting points for energy efficiency research. These models represent fairly realistic buildings and typical construction practices. Fifteen commercial building types and one multifamily residential building were determined by consensus between DOE, the National Renewable Energy Laboratory, Pacific Northwest National Laboratory, and Lawrence Berkeley National Laboratory, and represent approximately two-thirds of the commercial building stock.

Achieving the 30% Goal: Energy and Cost Savings Analysis of ASHRAE Standard 90.1-2010

This Technical Support Document presents the energy and cost savings analysis that PNNL conducted to measure the potential energy savings of 90.1-2010 relative to 90.1-2004. PNNL conducted this analysis with inputs from many other contributors and source of information. In particular, guidance and direction was provided by the Simulation Working Group under the auspices of the SSPC90.1. This report documents the approach and methodologies that PNNL developed to evaluate the energy saving achieved from use of ASHRAE/IES Standard 90.1-2010. Specifically, this report provides PNNL’s Progress Indicator process and methodology, EnergyPlus simulation framework, prototype model descriptions. This report covers the combined upgrades from 90.1-2004 to 90.1-2010, resulting in a total of 153 addenda. PNNL has reviewed and considered all 153 addenda for quantitative analysis in the Progress Indicator process. 53 of those are included in the quantitative analysis. This report provides information on the categorization of all of the addenda, a summary of the content, and deeper explanation of the impact and modeling of 53 identified addenda with quantitative savings.

National Cost-effectiveness of ANSI/ASHRAE/IES Standard 90.1-2013

The purpose of this analysis is to examine the cost-effectiveness of the 2013 edition of ANSI/ASHRAE/IES1 Standard 90.1 (ANSI/ASHRAE/IES 2013).

Enhancements to ASHRAE Standard 90.1 Prototype Building Models

This report focuses on enhancements to prototype building models used to determine the energy impact of various versions of ANSI/ASHRAE/IES Standard 90.1. Since the last publication of the prototype building models, PNNL has made numerous enhancements to the original prototype models compliant with the 2004, 2007, and 2010 editions of Standard 90.1. Those enhancements are described here and were made for several reasons: (1) to change or improve prototype design assumptions; (2) to improve the simulation accuracy; (3) to improve the simulation infrastructure; and (4) to add additional detail to the models needed to capture certain energy impacts from Standard 90.1 improvements. These enhancements impact simulated prototype energy use, and consequently impact the savings estimated from edition to edition of Standard 90.1.

Analysis of Daylighting Requirements within ASHRAE Standard 90.1

Pacific Northwest National Laboratory (PNNL), under the Building Energy Codes Program (BECP) funded by U.S. Department of Energy (DOE), provides support to the ASHRAE/IES/IESNA Standard 90.1(Standard 90.1) Standing Standards Project Committee (SSPC 90.1) and its subcommittees. In an effort to provide the ASHRAE SSPC 90.1 with data that will improve the daylighting and fenestration requirements in the Standard, PNNL collaborated with Heschong Mahone Group (HMG), now part of TRC Solutions. Combining EnergyPlus, a whole-building energy simulation software developed by DOE, with Radiance, a highly accurate illumination modeling software (Ward 1994), the daylighting requirements within Standard 90.1 were analyzed in greater detail. The initial scope of the study was to evaluate the impact of the fraction of window area compared to exterior wall area (window-to-wall ratio (WWR)) on energy consumption when daylighting controls are implemented. This scope was expanded to study the impact of fenestration visible transmittance (VT), electric lighting controls and daylighted area on building energy consumption.

Energy and Energy Cost Savings Analysis of the IECC for Commercial Buildings

The purpose of this analysis is to assess the relative energy and energy cost performance of commercial buildings designed to meet the requirements found in the commercial energy efficiency provisions of the International Energy Conservation Code (IECC). Section 304(b) of the Energy Conservation and Production Act (ECPA), as amended, requires the Secretary of Energy to make a determination each time a revised version of ASHRAE Standard 90.1 is published with respect to whether the revised standard would improve energy efficiency in commercial buildings. As many states have historically adopted the IECC for both residential and commercial buildings, PNNL has evaluated the impacts of the commercial provisions of the 2006, 2009, and 2012 editions of the IECC. PNNL also compared energy performance with corresponding editions of ANSI/ASHRAE/IES Standard 90.1 to help states and local jurisdictions make informed decisions regarding model code adoption.

ANSI/ASHRAE/IES Standard 90.1-2013 Determination of Energy Savings: Qualitative Analysis

This report provides a final quantitative analysis to assess whether buildings constructed according to the requirements of ANSI/ASHRAE/IES Standard 90.1-2013 would result in improved energy efficiency in commercial buildings. The final analysis considered each of the 110 addenda to Standard 90.1-2010 that were included in Standard 90.1-2013. PNNL reviewed all addenda included by ASHRAE in creating Standard 90.1-2013 from Standard 90.1-2010, and considered their combined impact on a suite of prototype building models across all U.S. climate zones. Most addenda were deemed to have little quantifiable impact on building efficiency for the purpose of DOE’s final determination. However, out of the 110 total addenda, 30 were identified as having a measureable and quantifiable impact.

ANSI/ASHRAE/IES Standard 90.1-2010 Final Determination Quantitative Analysis

The U.S. Department of Energy (DOE) conducted a final quantitative analysis to assess whether buildings constructed according to the requirements of the American National Standards Institute (ANSI)/American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE)/Illuminating Engineering Society of North America (IESNA) Standard 90.1-2010 (ASHRAE Standard 90.1-2010, Standard 90.1-2010, or 2010 edition) would result in energy savings compared with buildings constructed to ANSI/ASHRAE/IESNA Standard 90.1-2007(ASHRAE Standard 90.1-2007, Standard 90.1-2007, or 2007 edition). The final analysis considered each of the 109 addenda to ASHRAE Standard 90.1-2007 that were included in ASHRAE Standard 90.1-2010. All 109 addenda processed by ASHRAE in the creation of Standard 90.1-2010 from Standard 90.1-2007 were reviewed by DOE, and their combined impact on a suite of 16 building prototype models in 15 ASHRAE climate zones was considered. Most addenda were deemed to have little quantifiable impact on building efficiency for the purpose of DOEs final determination. However, out of the 109 addenda, 34 were preliminarily determined to have a measureable and quantifiable impact. A suite of 240 computer energy simulations for building prototypes complying with ASHRAE 90.1-2007 was developed. These prototypes were then modified in accordance with these 34 addenda to create a second suite of corresponding building simulations reflecting the same buildings compliant with Standard 90.1-2010. The building simulations were conducted using the DOE EnergyPlus building simulation software. The resulting energy use from the complete suite of 480 simulation runs was then converted to energy use intensity (EUI, or energy use per unit floor area) metrics (Site EUI, Primary EUI, and energy cost intensity [ECI]) results for each simulation. For each edition of the standard, these EUIs were then aggregated to a national basis for each prototype using weighting factors based on construction floor area developed for each of the 15 U.S. climate zones using commercial construction data. When compared, the resulting weighted EUIs indicated that each of the 16 building prototypes used less energy under Standard 90.1-2010 than under Standard 90.1-2007 on a national basis when considering site energy, primary energy, or energy cost. The EUIs were also aggregated across building types to a national commercial building basis using the same weighting data. On a national basis, the final quantitative analysis estimated a floor-space-weighted national average reduction in new building energy consumption of 18.2 percent for source energy and 18.5 percent when considering site energy. An 18.2 percent savings in energy cost, based on national average commercial energy costs for electricity and natural gas, was also estimated.

National Cost-effectiveness of ASHRAE Standard 90.1-2010 Compared to ASHRAE Standard 90.1-2007

Pacific Northwest National Laboratory (PNNL) completed this project for the U.S. Department of Energy’s (DOE’s) Building Energy Codes Program (BECP). DOE’s BECP supports upgrading building energy codes and standards, and the states’ adoption, implementation, and enforcement of upgraded codes and standards. Building energy codes and standards set minimum requirements for energy-efficient design and construction for new and renovated buildings, and impact energy use and greenhouse gas emissions for the life of buildings. Continuous improvement of building energy efficiency is achieved by periodically upgrading energy codes and standards. Ensuring that changes in the code that may alter costs (for building components, initial purchase and installation, replacement, maintenance and energy) are cost-effective encourages their acceptance and implementation. ANSI/ASHRAE/IESNA Standard 90.1 is the energy standard for commercial and multi-family residential buildings over three floors.

Assessing overall building energy performance of a large population of residential single-family homes using limited field data

Building energy simulation plays a significant role in building design and retrofit. Most applications deal with individual buildings which allow for the specification of detailed model inputs. However, building energy simulation can be a powerful tool for assessing energy performance even when comprehensive building characteristics are unavailable. In this study, limited field data were collected on randomly selected new homes in eight US states with a goal of evaluating energy code compliance and energy savings potential. The limited data do not allow the derivation of comprehensive model inputs for each individual home sampled, let alone for the entire unknown residential construction stock. Therefore, we used prototype buildings to construct a large number of models and utilized bootstrap sampling to draw inputs from the limited data. This research demonstrates that overall energy performance of a large population of new homes can be assessed by the novel framework, given limited data.