With ever-increasing codes, are conservation strategies and measures changing enough over time to maintain both energy use and energy cost savings? To answer this question, a group of projects were analyzed by the Weidt Group to compare savings from old code versus new code, specifically using the 2013 code compared to projects previously completed through Xcel Energy’s Energy Design Assistance program.
The study found that the relative impacts of many energy efficiency measures have stayed consistent, even though some of the technologies for delivering them and the overall savings potential have changed with the evolving energy codes. Even though energy codes are becoming increasingly stringent, technology is, in fact, keeping up.
Many of the top energy strategies that first became popular five to 10 years ago are still relevant today. For example, LED lighting dominates the building industry as the primary technology. Five to 10 years ago, it was fluorescents. Even though code requirements for building lighting have become significantly more stringent, LED technology is allowing teams and owners to still see energy savings and returns on their investments.
Each building and project is unique, and that is the value of energy design assistance and whole-building modeling. To achieve project goals, energy use and energy cost savings must be simultaneously considered. Below are the top three strategies for both energy use and energy cost savings found from the project analysis in regards to the new 2013 code.
Top three energy use saving strategies (new code, 2013)
- High-efficiency heating equipment (responsible for approximately 30 percent of total annual energy use savings): Code minimums are still 80 percent thermally efficient, and high-efficiency boilers have become an industry standard. Although they are usually one of the top mechanical strategies with the highest potential for conservation, this is purely from an energy use perspective. The lower cost of natural gas means that the energy savings potential and return on investments appear lower.
- Interior lighting controls package (responsible for approximately 20 percent of total annual energy use savings)
- Interior lighting power reductions (responsible for approximately 15 percent of total annual energy use savings)
Top three energy cost saving strategies (new code, 2013)
- Interior lighting controls package (responsible for approximately 25 percent of total annual energy cost savings): This strategy is considered from a lighting controls package perspective, not individual controls in specific spaces. Lighting controls packages can easily account for 25 percent of kWh savings or higher, depending on project scope, as well as 25–35 percent of peak kW demand savings. LED technology is the driving force behind these cost savings. Although code allowances are getting ever more stringent, the technology still makes it possible to achieve good savings relative to baseline.
- High-efficiency cooling equipment (responsible for approximately 15 percent of total annual energy cost savings)
- Interior lighting power reductions (responsible for approximately 15 percent of total annual energy cost savings)
These findings serve to demonstrate that when energy use and energy cost savings are considered together, the most effective strategies overall are interior lighting controls packages and interior lighting power reductions. High-efficiency heating and cooling equipment have significant energy use and energy cost savings, respectively, but their tradeoffs mean a lower overall return on investment.
The Sankey diagram below was built in reference to the 2013 projects: