Energy targets critical for efficient design

Buildings in the U.S. are responsible for 36% of the nation’s carbon dioxide emissions. Despite the continued improvement of energy codes, as much as 80% of cost-effective measures to improve energy efficiency remain untapped. Why the disconnect?

Energy codes specify minimum standards for the building envelope, HVAC and lighting. Though updated codes are better today, there is still a gap between minimum code and best practice. Codes typically don’t address plug-and-process loads, building orientation or technology choice. Nor do they address the oversizing of equipment, which can lead to higher energy use.

The difference between the target and actual energy use can also be explained by the skill of the energy modeler, the quality of construction, whether the building was commissioned before operations, the frequency of maintenance or a combination of these factors. 

The best advice from the Environmental Protection Agency’s (EPA’s) ENERGY STAR^® program is to follow code and to set a performance target based on peer buildings. 

Setting a whole-building (or campus) target can be done within the ENERGY STAR Portfolio Manager^®. There is no one-size-fits-all energy use intensity (EUI) target. If you want to design a hospital that achieves a certain ENERGY STAR score (say, 85), Portfolio Manager will generate a customized EUI for your hospital in terms of size, specific operations and geographic location — derived from real data. 

That customized EUI will be your target to achieve through a combination of design choices, energy conservation measures (ECMs), technology choices and other factors. Depending on how high you’re aiming, it may require your design team to go through several iterations and increasing levels of ECMs to reach the desired goal. 

Designs that are expected to achieve an ENERGY STAR score of 75 or higher can earn “Designed to Earn the ENERGY STAR” recognition from the EPA. Once awarded, the mark can be used on design plans and promotional materials to publicize the level of performance expected once the building is operational.

Clark Reed is National Program Manager at the Environmental Protection Agency.