In 1990, more focus was being placed on energy efficiency and in response, the Department of Energy created the National Appliance Energy Conservation Act (NAECA). After that point in time, new technologies that increased energy efficiency were discovered, and the DOE updated the NAECA in 2004. Once again, new technologies have been developed and the rules are being updated. Written in 2010, the new standards go into effect on April 16, 2015.
How does this affect builders?
Based on the new regulations (which are applicable to all homes, including manufactured homes (per 3280.707(d)), water heaters will mostly be larger (both width and height), requiring a larger area in which to place the water heater. You might want to take this into account now as you are developing new floor plans or making revisions to existing ones. You should contact your supplier for specific information, as the new unit (depending on capacity) could be 2 or more inches larger than the previous model.
Below is a table showing the new regulations for both electric and gas.
If you have further questions about how these changes will impact your home manufacturing, feel free to contact NTA.