When it comes to efficiency standards for buildings, it’s often not clear whether the glass is half full or half empty. In California, for example, these standards, commonly referred to as Title 24, take three forms: 1. Mandatory measures, which every building is required to use; 2. Prescriptive measures, which sound like something your doctor tells you to do, which most people consider nearly mandatory. But most designers don’t follow the prescriptive measures; instead, they follow 3. Performance approach, based on a computer simulation of their design using approved compliance software. The building they design must perform at least as well as a building of the same size, type and location built using the prescriptive method. The prescriptive approach therefore sets the energy budget for the building.
Every three years Title 24 is revised to reflect changes in best-available technology. Most people probably think bureaucrats sit around and dream this stuff up because they don’t have real jobs selling stuff. Actually no, it’s because the legislature and the governor tell them to. Back in 2006, the California legislature passed the Global Warming Solutions Act, a law commonly known as AB-32. It requires various state agencies to figure out how best to reduce emissions of greenhouse gasses to 1990 levels, by the year 2020.
Most of these emissions are related to fossil fuels burned for energy, and in California about a third of energy is used in buildings. (Half is used in transportation, and a sixth in industry, agriculture and water treatment and pumping.) In response to AB-32, the Public Utilities Commission came out with the California Long Term Strategic Energy Efficiency Plan, which set forth as a goal that all new California residential buildings be zero-net energy by 2020 and that all new commercial buildings be zero-net energy by 2030.
The Energy Commission set these targets for Title 24 as well. Historically Title 24 has been steadily reducing unit-building energy use, but it must now just about double that rate of reduction to meet these ambitious goals.
You might expect the cup of Title 24 to be pretty full. It is. Some of the more significant measures are:
• Economizer diagnostics for A/C units. A study by New Buildings Institute and Architectural Energy Corp. published in 2003 found over 60% of small air conditioning units had problems with economizers, which use outside air for cooling when the outdoor temperature is low enough. Economizers are required for non-residential A/C units over a five-ton capacity. But when the dampers are stuck open or closed they can waste energy and potentially degrade indoor air quality. Software which monitors sensors for the temperature of outdoor air, indoor air, and supply air can easily determine if economizers are working properly and notify service personnel. These diagnostics will be required for A/C units over 4.5 tons capacity.
• Multistep dimming for lighting. Most indoor areas using linear florescent lamps over 13 W will be required to have at least four steps of dimming. This is a big step because until recently dimming ballasts were just too expensive to be economical. It was a classic chicken-and-egg situation, where low production volumes kept the price of these ballasts high, and high prices kept volumes low. The recently-finished New York Times Building was instrumental in changing that dynamic, both because this single building offered an order large enough to move the market, and because its construction managers bargained hard on price and performance. Thanks to them this technology has broken through the price barrier, and the new California standards will ensure it stays there. Dimmable lighting and integrated controls are keys to saving energy and improving indoor environments with use of natural daylight, and the new standards will move things a long way in that direction.
• Commissioning. Most owners of new buildings expect their building will work as intended. Oops, did anyone actually figure out what the owner needed? Did anyone check to make sure systems were installed and functioning as intended? All too often the answer has been no, and the new California standards will now require a reasonably complete commissioning process for buildings over 10,000 ft2. This will go a long way towards ensuring that owners get what they pay for.
There are also measures which were cut at the insistence of the Building Industry Association, such as ability of thermostats to be upgraded for communication. But I think you get the idea. This cup is well beyond half full.
Initial summary of proposed changes to Title 24, www.energy.ca.gov/2012publications/CEC-400-2012-002/CEC-400-2012-002.pdf
2002 NBI/AEC study on small A/C performance,
Partial Rollback of standards due to BIA,
2013 proposed upgrade to Title 24 standards,