Building Research in the Digital Age
It is not easy to assess the real-world building marketplace. Fortunately, we have adopted methods that combine technology and analytics to better process and normalize the data we collect. By pairing energy, weather and building information, analytical modeling efforts can promote understanding of how multiple factors combine to affect energy use.
At Advanced Energy, we have developed the “House Characterization” approach to home energy assessments. Our engineers and building science specialists gather home attributes, such as square footage, number of stories, number of occupants and roof type, to simplify assessments and allow them to more easily determine a home’s likely energy use without needing long-term, dedicated home energy monitoring equipment. In a broader sense, documenting these traits is an effective way to target groups of homes based on qualitative data, which may form logical subsets useful for quantitative inference.
Using data from utility bills is another way to analyze energy usage. Although generally available only at the building level, utility bill analysis can provide insight into building performance. Billing data can be analyzed using algorithms like the Princeton Scorekeeping Method (PRISM), which provides a framework for assessing the weather-normalized effects of building modifications on energy use.
Weather normalization is a process in which utility billing data, before and after retrofits are completed, is adjusted to account for changes due to weather and is presented with reference to typical climatic conditions. Without weather-normalizing, the true effect of a retrofit on energy usage over time is hard to know.
Billing analysis techniques can help assess changes in energy use within large numbers of homes or buildings and be used to attribute estimates of effectiveness to implemented measures. Subgroups of homes can be formed to examine the effect of a retrofit on certain attributes of a study group, and differences in energy use not associated with changes of interest may be adjusted using control groups.
Submetering is more resource intensive than utility billing analysis, but it provides more detailed information on energy usage. An electrical submeter measures kilowatt-hour usage, often in 15- to 30-minute increments, continuously for a home or building (in some cases, individual systems within a home or building can be measured).
We have licensed electricians on staff who can install submeters at building sites to gather interval data manually during site visits, or in an automated fashion using internet-capable instrumentation. The detailed time resolution of interval submetering can be used to increase weather normalization accuracy or evaluate scheduling concerns at the whole-building level. Its focused nature can also increase the assessment accuracy of equipment performance or retrofit effectiveness.
Measuring building energy use, whether through utility bill analysis or submetering, is aided when data can be paired with building characteristics. By incorporating these methods into our research, we can make inferences and test new theories, and better understanding when and how energy is used can improve decision-making on saving energy and living more efficiently.