Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
I don't have any specific values for percent savings. But I think it useful to examine why doing modeling earlier is better. Building characteristics that have to do with form and fabric are harder to change as the design progresses and harder to change over the life of the building. Over time, controls, operation, and even HVAC systems will get changed, and although they are all very important to the utility bill they are also hard to model well. But things like design/geometry, windows, and insulation are more likely to remain fixed over the life of the building and fortunately have more robust modeling in BEM tools. I think the business case is stronger for form and fabric analyses, but the fraction of savings that can be attributed to those types of measures varies a lot across buildings.
