Most people think about many things when building a new home…….
- Should I go granite?
- What kind of faucets should I get?
- I can’t really pick a color for my walls……
What people rarely think about is how to build an energy efficient home. I’m going to turn it over to our expert energy rater, Rafal Olan (see his bio here) to explain why you should get an energy model done on your new home.
In comes Rafal…..
Energy modeling for residential new construction is the ideal way of predicting the annual operating cost of the home as well as lowering those costs by implementing the most cost effective construction detail measures. Every new home should incorporate design and planing along with an energy modeling software. Unfortunately they don’t. Most homes are built by residential developers or general contractors that only build to the code MINIMUM. That is another way of building home the worst possible legal way. You cannot build any worse than that unless you’re in violation of the building codes. A home built to code only will have the least efficient heating and cooling equipment, leaky duct systems, the whole house building envelope will not be sealed, minimum insulation (a lot of times less than minimum), and all the energy features that can be incorporated into building an efficient home are disregarded because they are not enforced. When we actually calculate and enter the plan information into the modeling software we can see through numerous reports where the most energy usage goes to and where potential savings can occur.
The first part of the energy modeling for a new home is sitting down with the homebuilder, whether with a homeowner, a contractor or both, and going over the plans. Most of the time we will look at a completed set of construction plans so energy modeling does not dictate the architectural design of the style of home, the plan layout, or change your dream house façade. The detailing inside the walls is what’s important: what R-value insulation will be in the walls, on the ceilings, vaults, around the slab or in the crawl space. Air, or whole house infiltration, and duct system sealing will be the next hurdles to tackle since most builders and subcontractors have never done it. Finally, equipment efficiencies will need to be decided to fit into each specific budget. However, a home with a well-sealed and insulated building envelope (the conditioned space of the home) will not require super-efficient equipment to be installed. The heat or cool air is already contained within the home so the equipment does not need to have a large capacity any more, thus lowering the overall need for it. So once we have the plans and know what is the proposed basic insulation and equipment to be installed we can enter all that data into home energy computer software to do all the calculating for us.
Now we have our computer model of a new home to be built. From all the proposed construction details and specification we can now see how this home should perform in climate specific zones, what parts of the home use the most energy and which use the least. The reports generated from the software tell us this information in Btu’s and dollar figures so it could be easy to see where potential improvements could be implemented. The energy rater can look at each specific component of the home and change their value to see what changes occur. We can analyze each change in dollars saved of the annual energy expanses. This will let us see how much savings will occur if, for example, we change the wall insulation from R13 to R15, if we add slab insulation to an typically uninsulated slab, or we we’d install a tankless water heater instead of a traditional 40 or 50 gallon tank. Each of these changes will calculate different annual cost estimation. The builder can estimate cost of installing each of these changes. Comparing the two expanses and savings will let you decide if a measure is worth changing to. Some measures will not cost any more to install, some will pay back for themselves within a year or two, while others may be of a longer duration or some not worth at all. The energy modeling allows us to see the home as it performs when it comes to annual energy usage.
Going over this pre-construction energy modeling process will educate and allow us to make important decisions how to best build the new home. An Energy Rater together with the builder, the prospective homeowner, and/or architect can establish best construction detailing into the design and to work into the construction budget. The Energy report will closely predict the finished home’s annual energy bills and generate appropriate documentation for an Energy Loan. Energy modeling gives the most accurate predictions of how well the newly built home will perform when it comes to everyday living costs associated with it. So why do Energy Modeling on a set of new plans? To get the best analysis of the home’s building features and to know all the costs associated with living in that home.