The Home Energy Saver was the first Internet-based tool for calculating energy use in residential buildings. The approach taken by the web site is to provide users with results based on a minimum of user input, and then, for those interested in continuing, allowing them progressively greater degrees of control in specifying the house and energy consuming appliances characteristics. This allows users with limited knowledge or time to access results that are generally applicable to their situation, while more informed or persistent users can get greater accuracy and relevance by customizing their house description. This design philosophy results in a progressive three-tiered approach to estimating energy consumption.
At the initial level of inputs, users are asked solely for their zip code (Figure 1). An initial set of results are immediately derived from the zip code input. These results are averages for the housing stock in their region, based on the 2005 Residential Energy Consumption Survey (RECS) (US DOE. 2009). HES also presents potential savings for a typical house in that region.
Simultaneously, users are shown the questions for the second, “simple inputs” level of the Home Energy Saver (Figure 2). This set of questions focuses on those appliances and housing characteristics that cause large variance in energy consumption (e.g. floor area, heating equipment, etc.). These key inputs can be used to refine the energy estimation further.
After answering the questions in the “simple inputs” level of HES, users can either calculate the energy used by their house (Figures 3 to 5) based on the description provided by the “simple level” of questions or further refine the house description before calculating by accessing the third, “detailed inputs” level of the model. In the detailed input pages, they can adjust nearly all of the envelope, site and appliance characteristics that go into estimating energy consumption for their home.
When the user is satisfied with the house description, they calculate the energy consumption, which replaces the prior default results based on a house in their area. At this time they can also view more detailed reports (Figures 6 and 7).
For both the “simple inputs” and “detailed inputs” levels, the models used to estimate energy consumption are identical, with user-entered values substituting for default values as the user progresses through the “detailed inputs” level. There are six major categories (end-uses) where energy consumption is estimated; heating, cooling, water heating, major appliances, lighting, and miscellaneous equipment. The Home Energy Saver uses engineering models to estimate energy consumption for all these end-uses.