We know that our home's fuel and electricity usage vary a lot from Spring to Summer to Fall to Winter. For those of us that have four seasons, the fuel bill rises from almost nothing in the summer to sky high in winter. Electricity use is high for air conditioning in the summer and tapers down in the winter.
Commercial buildings work differently. Most commercial buildings have “core” areas that do not have an exterior wall or roof. The “core” areas are internal rooms that have lights, PCs, people, copy machines – all of which give off heat. Those areas need cooling all 12 months! The corner office, on the other hand, has lights, people and PCs, but gains heat in the summer and loses heat in the winter from the walls and windows.
Energy use for a residence is very clearly dependent on the weather, whereas a commercial building is normally less dependent. How much less?
On the one hand, we know of commercial buildings that were shocked at how high their heating bill was last winter in Michigan. Other buildings saw a bump upwards, but it was manageable.
We made a small study a few years ago as part of a conference presentation to determine just how much weather varied from year to year. In a 12 year period, the Lansing, MI weather had varied between 3,000 and 7,700 heating degree days. “Heating degree days” are a measure of how cold the heating season is, and for this large range, the cost for heating a 20,000 square foot building varied about 12% - a lot less variation than you might have imagined!
Back when the EPA started putting mpg ratings on cars, there was always a caveat, “Your mileage may vary, depending on driving habits, etc.” The same is true for a building’s response to weather variations. Weather affects all buildings, but the impact varies depending on a host of factors. Regardless of your building’s details however, the more efficient your building, the less impact you’ll see!
A thorough energy analysis can easily determine the precise impact of weather on your building. Weather data for yesterday, last week or last year is readily available and can be plugged into an analysis of your building.
Want to know what your bills could have been last winter if you hadn’t put off those energy-related improvements? No problem. Want to know what the likely impact will be next winter after you’ve made those changes? That’s no problem, either. Want to check whether those changes are actually doing what you expected? Still no problem! Knowing the weather’s impact means there is one less thing to wonder and worry about.