Many of us believe we know what to do to reduce energy bills. We have been educated by the television and other sources to believe that it is rather straight forward. Replace old light bulbs with compact florescents, add insulation, etc. Many energy reduction programs offered by utility companies focus on one aspect like replacing heat pumps with more efficient ones, or, upgrading attic insulation. All of which are good things to do, but these prescriptive improvements do not consider how the house performs as a “system” of components, and are usually costly improvements. Understanding how a house performs, and finding the least costly improvements at the start of the process, requires some understanding of Building Science. First, lets talk about some common myths about energy reduction.
Do you think buying windows will save you energy and thereby money? If you said yes, you would be in the majority. However, spending money on windows is not the most cost effective or necessarily the most energy efficient way to spend money. Due to their high cost and low return on investment in terms of saving energy, they are not the first place you should invest money to get the most cost effective energy savings. The reason many of us believe the myth about windows is that through extensive advertising, window companies have convinced most of the public that this is the way to save money on energy. While it is true you will save energy, in most cases, they are expensive and you most likely still need to spend more money to get the final result you desire- less money out of pocket for energy.
What about a solar powered attic fan? Assuming you live in the Southern US or Western US, wouldn’t that lower cooling bills and energy use? Again, most people believe yes, but the correct answer is no in most cases. Before air conditioning became the norm, using fans was smart because you needed to move air to keep your home cool. However, as homes have become “tighter” and in the last 30 years we have come to rely more on air conditioning for comfort, a powered attic fan, whether solar or not, is a bad idea. To understand what is going on, we have to talk about Building Science. At the risk of over-simplification, what happens is you are creating a negative pressure in the attic that drives conditioned air (that costs money to cool) into the attic. That raises the cost to condition the living space because unconditioned air from the outside is finding leaks and cracks to replace the conditioned air “sucked up” into the attic. To make matters worse, if you live on a crawl space type foundation, much of that unconditioned air is coming from the crawl space and that air may have mold and other unhealthy conditions going on. Some experts say as much as 60%-70% of the air we breathe on the 1st living level comes from the crawl space, and that is without the use of a powered attic fan!
I recently performed an Energy Audit on a historic home that had been recently remodeled and retrofitted with spray foam in the walls, floor and attic. The owner who was a builder, was complaining of continued high energy bills despite his installation of on-demand water heating, high SEER heat pumps, good air sealed thermal enclosure using spray foam and better than average R-value windows. During my site visit I noticed one significant oddity: an under the slab Radon mitigation system installed in the unconditioned basement. As I modeled the home in RemRate software, I was able to confirm what I already suspected was the problem and make clear recommendations to fix the problem. What I suspected was that the negative pressure created by the Radon mitigation system, was pulling conditioned air from the main level into the unconditioned basement. My recommendation was to treat the basement as a conditioned area; to insulate walls and rim and band joists. The modeling software confirmed that this approach would result in a 15 point drop on the HERS index.
Let the Buyer beware, there are a lot of so called Energy Auditors who are really just sales men or women for a window company, insulation company, solar installer, etc. They may sell you a “bill of goods” that looks good on paper, but falls far short of cost effective, significant energy savings. An independent energy auditor using a “whole house approach” should be able reveal where the “low hanging fruit” is. Using tools such as a Blower Door, Duct Blaster and Infrared Camera are essential in finding the best, most cost effective areas to improve a home’s energy performance. Armed with this equipment and some understanding of Building Science, an independent Energy Auditor working in strategic partnership with an independent Contractor, can often find the simplest and least costly fixes first, then, give you other more expensive options. Where can you find a team of independent retrofit Contractors and Energy Auditors working together to improve America’s housing stock? Start with RESNET (or the residential energy services network). RESNET has recently developed strategic work teams called RESNET Energy Smart Home Performance Teams. More information about these teams and how to find one in your local market is available at http://www.resnet.us/ . Then, look for an independent Energy Rater (raters are qualified to perform audits) at the RESNET site. Some contractors have Energy Raters on their staff and that is the arrangement you want to avoid. The Energy Rater should be able to put you in touch with an independent Contractor that they have a working relationship with.