The Center for Energy and Environment has developed a home energy efficiency index for use with its residential energy program, targeted at cost-effective retrofits for existing homes. We spoke with Carl Nelson, Manager of Residential Programs, to learn more.
Joel Haskard: What does the Home Energy Improvement Index do?
Carl Nelson: It tells you your home’s energy performance in a easy-to-understand label. Think of it as a miles-per-gallon rating for your house, specific to Minnesota climate and Minnesota homes. More than that, it helps you prioritize what energy improvements you should do in your home. We use a quantitative method to score your home on the 5 home features that are most important for your home’s energy performance in Minnesota: attic insulation, air sealing, furnace or boiler, wall insulation, and windows. Each of these 5 items gets a score, and when you add it up, 100 is a perfect score, and represents completing all of the cost-effective energy improvements in your home. If you get less than that, you can see which improvements should be done immediately, and which can wait until later. It is a great tool to use to enhance the performance of an existing homes energy-efficiency program, which is how we use it.
Joel: You use the SIMPLE energy simulation model for this program. Can you tell us more about what this is and what it does?
Carl: The SIMPLE model is exactly what it sounds like, it is a simplified energy modeling method. This model is what determines the distribution of points that are available for a given home, based on the energy-savings potential. It uses the least number of data inputs collected in the home to achieve a robust result. Our research has found that for existing homes, you can achieve comparable precision from models that require 100 or more inputs (such as used for RESNET models to produce a HERS score), or using a model like SIMPLE, which has about 25 inputs. (By the way, we did this research under contract with the University of Minnesota and the National Renewable Energy Laboratory, and a paper on our results will be published shortly). So why would you pay more to collect 75 more inputs at the house when you don’t need to? Cost-effective residential programs are about achieving efficiencies in program delivery, and we are constantly looking for ways to deliver value without spending a lot of money.
Joel: How can people access and use the Home Energy Improvement Index? Is there a cost? Do they need to be in a specific utility’s service territory?
Carl: Currently, only Xcel Energy electric and CenterPoint Energy gas customers can receive the score in the Twin Cities area, through the residential programs that we run for them. Next year, we hope to partner with other organizations to deliver the score elsewhere. We are already engaged in several conversations with audit providers that serve customers throughout the state, as well as some nationally.
Joel: Ultimately, what is your goal for the Home Energy Improvement Index?
Carl: We have the modest goal of helping to transform the market for residential energy retrofits. We’ve spent over 2 years developing this label, so we’ve done a lot of thinking about how this can happen, and there are several ways:
- First, it is hard to find an audit report that gives you a clear prioritization of what retrofits you should do; ours does, and we hope this will increase the number of people that choose to follow-through with the recommendations.
- Second, it taps into our inner fifth-grader that wants to achieve that perfect score; having a scorecard can help further motivate people to complete the upgrades.
- And finally, our long-term goal is to see if we can incorporate our score into the home transactional process at time-of-sale, so that when people do the effort to bring their home up to a perfect 100, they can get “credit” for that when they sell their home.
Click here to learn more about the Home Energy Improvement Index >>
See a presentation about CEE’s simplified approach to visualizing household retrofit potential >>
