The Climate Policy Initiative has completed a study to measure and evaluate the impact of residential building energy codes on total household energy consumption, “Codes to Cleaner Buildings: Effectiveness of US Building Energy Codes”, was released by the Climate Policy Initiative (CPI) of San Francisco, California on September 7, 2011. Conducted by Jeff Deason and Andrew Hobbs of CPI, the study was done to see if building energy codes make an impact on home energy use and greenhouse gas emissions.
Many states have adopted model energy codes (primarily the 2009 International Energy Conservation Code or IECC) and few have their own code that has been personalized to be specific for that state, such as California. Only 7 states have not adopted a statewide mandatory building energy code. A small number of states have adopted a less stringent code than the 2009 IECC. A 2012 version of the IECC was released in August of 2011 and there are states that are considering adopting this model standard and who have statutes that mandate its adoption.
CPI’s analysis reviewed states’ energy use from 1986 to 2008 using real data unlike previous studies that have focused on specific energy sources such as electricity alone or which have used engineering models to gather data. The study evaluated code effectiveness by comparing residential energy use in states that have adopted residential building codes to energy use in states that have not adopted codes.
The findings of the study show that the use of energy codes are: reducing energy consumption, driving fuel substitution away from fuels like oil and wood and towards natural gas, and reducing household emissions. Energy use per household was shown to be 10% lower in states with a code than in states without a code. The use of high efficiency natural gas heaters and electric heat pumps, which are encouraged in current energy codes, have reduced household greenhouse gas emissions by 16% in states that have adopted a statewide model code. To insure that the effects were due to codes and not to other factors, CPIs analysis controlled for the effect of changes in energy prices, weather, income, rates of new home construction, federal policies, time trends, and differences between states that do not vary over time such as culture and policy settings.
The study is a part of a broader project by CPI to evaluate the impacts of building policy in key regions around the world. A study done by CPI Berlin indicates that targeting different stages of the retrofit process may help Germany reach its target of 80% reduction in residential energy use by 2050 and a study is underway by CPI at Tsinghua on methods used to assess the impact of Chinese building codes.