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Dear Pablo: You have written about home energy efficiency in the past, but aside from individual technologies like CFLs, what can I do to get the "whole picture" and how do I prioritize my investments?You are correct, there are many great technologies, low-tech solutions, and behavioral changes that can greatly reduce your home's environmental impact but to get the "whole picture" you need a systems approach. I recently had a home performance contractor called Sustainable Spaces come to my home to perform an audit. Their "Green Up" process was eye opening and has helped me prioritize my home improvement list and investments.
How to Find a Home Performance ContractorSustainable Spaces, a San Francisco Bay Area-based home performance contractor is a member of the Building Performance Institute which has accredited contractors all over the country. Sustainable Spaces is also a founding member of Efficiency First, a national advocacy organization that works on elevating the dialog on the importance of efficiency in reducing greenhouse gas emissions and promoting a green-collar workforce on a national and state level. Energy First has a long list of members, some of which are technology companies, but many of which are home performance contractors. Between these two resources you should be able to find a contractor near you.
The Home Energy Audit ProcessOn the day of my audit a team from Sustainable Spaces came to my home and met with me about my concerns. They wore clean uniforms and booties over their shoes. They even put down a moving blanket before bringing in their gear. The gear was perhaps the most impressive. It included a blower door, essentially a door-sized frame with a fan in it, that pressurizes the house and measures the difference in inside and outside air pressure, thereby determining your leakage rate. My house had a leakage rate of 0.45, meaning that every hour 45% of my homes air is replaced by air from outside, from the attic, or the crawlspace. The suggested leakage rate is actually 35% (lower than that and you need to bring in outside air to avoid stagnation or indoor air quality issues), so I'm not actually doing that bad.Other tools included a device that measured the air flow from each HVAC register (the forced-air grates in my floors) in order to determine not only the balance of the system (which rooms are getting too much or too little air) and the leakage of the ducts. I was surprised to learn that most HVAC ducts are incorrectly installed and leak up to 50% of air (sometimes more) into your crawlspace or attic. Sustainable Spaces recommends removing duct tape (which is actually not suitable for use on ducts) and replacing it with an adhesive called mastic and industrial zip ties. Cutting down on the leakage not only saves money by keeping the heated/cooled air from going where you don't want it, but it also improves indoor air quality by keeping crawlspace air out of your house.Another tool that I particularly enjoyed playing with was an infrared camera that, when aimed at walls, or ceilings, shows where insulation is insufficient. I was able to see cold air infiltrating through my electrical outlets and the warmth created by phone chargers left plugged in. Aside from being fun to play with, all of these high-tech tools help pinpoint specifically where the greatest opportunities for saving energy exist. The final deliverable from Sustainable Spaces included a concise report documenting all of their findings. In addition to the findings, they provide recommendations, in order of efficacy and cost effectiveness, and along with an estimated cost (Sustainable Spaces has a contractors license and can perform most of the work that they recommend, and follow it up with another audit to show the improvement).
The Home Audit ResultsSince most of my lights have already been replaced with CFLs or LEDs, my report's first recommendations included sealing air leaks in the building envelope and the air ducts. I plan to use expanding spray foam to seal any openings between my attic and walls (where electrical cables run) and silicone sealant to seal my skylights. Next, I plan on repairing my improperly installed and rodent-damaged sub floor insulation, or even replacing it with spray-in insulation. Once I have addressed these issues my home will have a leakage rate less than 35% and I may need to install a heat recovery ventilation system to bring in outside air. Next I will replace my over-sized furnace and air conditioner with a heat pump, an electrical unit that efficiently creates hot air in the winter and warm air in the summer. Once I have reduced my energy requirements by sealing my home and replacing inefficient appliances I can finally get those solar panels that I want in order to power everything. If I do so I will be almost completely off of natural gas and my home will be close to being a zero emissions home.Ask Pablo is a weekly column that aims to answer your pressing eco-quandries. Want to ask Pablo a question? Simply email Pablo(at)treehugger(dot)com. Wondering why Pablo's qualified to answer? As the Vice President of Greenhouse Gas Management at ClimateCHECK, he helps major corporations measure and manage their greenhouse gas emissions.
Additional Resources on Home Energy Efficiency
Is Your House Making You Look Fat?
Discussion: Investing in Efficiency - Car or House?
80% Energy Efficiency Improvement Possible this Century
The Affordable Zero Energy House