Existing Buildings Use the Load

The increasing need for greater energy efficiency in existing buildings is the onus behind ASHRAE / IES Standard 100-2006R, Energy Efficiency in Existing Buildings, which underwent its first 30-day public review period earlier this year.

New buildings only account for 2% of construction projects in the U.S., while 86% of construction dollars go into renovating the existing building stock. Anywhere from 75% to 80% of the buildings that exist today will exist in 2030.

Gordon Holness, past president of the American Society for Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), is vice-chair of the committee rewriting the standard. He says Standard 100-2006R is intended as a building code resource for jurisdictions looking to improve the energy efficiency of existing buildings.

The standard was originally published in 1981 as part of the same energy conservation program that included ASHRAE Standard 90-75 – the predecessor to ASHRAE 90.1.

The first versions of both standards were largely prescriptive in nature, says Holness. “… an owner doing any lighting upgrades or boiler replacement would need to look at the requirements in 90.1 for those elements. There was no requirement to look at the entire building, so it is not really possible to compare energy efficiency levels.

“For these and other reasons the standard has, frankly, not received much attention or use. Now for the first time, the rewritten Standard 100-2006R will address the entire building performance,” says Holness.

Renovating the existing stock of buildings is an important element of reducing greenhouse gas emissions.

Nearly 94.6 quadrillion Btus of energy were consumed in the U.S. in 2009, and 42% was used by commercial and residential buildings.

In Canada there are about 450,000 institutional and commercial buildings consuming $17 billion in energy costs. According to Natural Resources Canada, these along with residential buildings produce 28% of the country’s greenhouse gases.

Rick Hermans, chair of the Standard 100-2006R committee, points out that even if every square foot of new construction were built at net zero energy, meeting the energy demand would still require improvements in the existing building stock.

While the standard is initially focused on the U.S. it can readily be adapted for application in Canada and other countries.

The new standard addresses major and minor modifications for residential and commercial buildings and multi-use buildings with variable occupancy loads.

Energy Use Intensity (EUI) targets are set using data from the quadrennial Commercial Buildings Energy Consumption Survey, which is undertaken by the U.S. Department of Energy. The survey tracks and identifies energy use (kBtu/sf-yr) for 53 building types in 16 climate zones.

Buildings with identified energy targets based on building type, occupancy, and climate zone will select from Energy Efficiency Measures (EEMs) to meet the intended goal.

Non-compliant buildings will undertake an energy audit to identify EEMs that should be applied based on a predicted simple payback period or internal rate of return.

The standard also provides multiple levels of compliance and energy efficiency requirements for buildings without energy targets, including industrial, agricultural, data centres, and special laboratories.

“For buildings without energy targets a more aggressive approach is taken, requiring an energy audit to identify an optimized bundle of EEMs that achieves the maximum energy efficiency possible, while offering a simple payback of five years or less,” says Holness. “This may require an iterative process of analysis.”

Buildings where energy efficiency measures are implemented in response to an energy audit will be granted conditional compliance, subject to an energy monitoring review in 15 months.

Criteria for energy management plans and operation and maintenance plans are included, as are appendices for lifecycle cost analyses and energy efficiency measures.

Holness says retrofitting existing buildings is the greatest opportunity for a sustainable future. “We see a tremendous potential for the standard to be applied as a validation process through programs like Building Star and Home Star,” he says. “Investing $50 billion per year for the next 10 years could retrofit some 50 million existing residential and commercial buildings, creating more than 625,000 new jobs, while saving $685 million per year in energy costs.”

Standard 100-2006R is set to complete its public review and be released later this year. cce

The new standard will address the entire building energy performance of existing buildings for the first time.