I’ve been performing a semi-deep energy retrofit to my home for the past 5 years, and at my current rate of progress, it will be another 5 years before I’m complete. This leads to a question; how does a person prioritize the work to be done? Are the easiest items to complete done first, or the stuff that provides the biggest return on investment a better place to start? This blog discusses my suggested priorities.
- Structural decay must be dealt with first.
This one’s pretty obvious, if the house is close to collapse, that’s the place to start. Sometimes though, this type of damage is hidden. This photo shows such a case. A builder friend of mine was hired to repair the painted cedar siding on this seasonal lake cabin. His crew removed the deteriorating cedar and house wrap to check on the condition of the plywood wall sheathing. There was some discoloration of the plywood and light rot in the lower window corners, but it looked intact. They decided to remove a small piece just to be sure which led to what they found in the photo. Substantial damage to the wall framing including a load path that supports the roof. There were no signs of water damage on the interior, only a few 30-year-old rotted cedar boards around the window on the exterior.
- Active water leaks are the second most important problem to solve.
Another commonsense work order, there’s no use making energy upgrades if the home is going to look like the photo above in a few years. The photos below are an example. This was a home I visited as part of an energy audit; the homeowners were looking for ways to reduce their electricity consumption. While I was in the attic, I found an active roof leak around a fireplace chimney, something the homeowner wasn’t aware of. The smart thing to do is repair the roof leak before performing any of the energy upgrades that I suggested.
If future plans include major upgrades or rebuilding areas that have active bulk water leaks, the repair may be a short-term fix. Something to get by until the more inclusive work begins. The issue with some of these “fixes” is sometimes the temporary repair ends up being long term. If this ends up being the case, you’ll want to have a way to maintain the repair until the permanent fix is completed.
- Low hanging fruit.
This is low-cost work that a handy homeowner can accomplish. Air sealing a rim or band joist or placing a vapor retarder over a dirt floor crawlspace. Tasks that can be accomplished in a weekend or two without any major training or potential risk to homeowner safety. I often recommend many “low hanging fruit” ideas to homeowners as part of the energy audits and assessments I perform, but with a warning. Some of the work may change how the home has been operating, creating unwanted impacts. For instance, improving the air tightness of a home can impact indoor air quality and increase humidity levels.
Suggestions I make often include monitoring indoor humidity levels and/or air quality, or ventilation strategies that improve IAQ. I might also suggest a return visit to conduct testing to confirm the work was successful. Improving a home’s energy efficiency should never come at the expense of the homeowner’s health.
Sometimes it’s best to skip the low hanging fruit upgrades because a larger scope of work performed by a building contractor or other professional is being planned. (See number 4.)
- Professional upgrades.
These are hired renovations, remodels, and/or additions to existing homes. This type of work can have the biggest impact on how a home performs, but also will cost the most and usually require hiring a contractor or other trade professional. There are several routes to take at this level, many of which use the phrase, “it depends”. The work may include either a shallow or deep energy retrofit. The place to start though is with an energy audit or assessment.
A common question I’m often asked by people outside my market, where can I find someone to perform an energy audit on my home? The place to start is with a local energy provider, either an electricity or gas supply company. Many offer free or low-cost basic energy assessments for their customers. Energy auditors who are performing this basic energy assessment can usually provide more comprehensive energy audits for an additional cost. If you are unable to locate someone through an energy provider, my next suggestion is to contact a local weatherization assistance program (WAP) in your market. Another option is through Building Performance Institute (BPI) or Residential Energy Services Network (RESNET). They have several energy auditor certification programs and have a listing of people that have passed the BPI and/or RESNET testing requirements.
Once it has been determined how a home is currently performing, the next step is to put together a scope of work for improvements. This is where the “it depends” comes in. Items 1 (structural decay) and 2 (bulk water leaks) still need to be considered first.
The more inclusive energy retrofits will include improvements in both air and thermal control layers. Recladding a home can create opportunities to improve the water control, air control, and thermal control layers (and maybe even the vapor control layer). Continuous insulation is one of the hottest topics in the building industry right now. There are several articles on GBA discussing how to plan and execute a successful CI strategy. Improving bulk water management and air control can also be addressed.
While we are discussing exterior wall improvements, how about windows. Should window replacement be part of the scope of work for an energy upgrade? Maybe. Swapping out a 10- or 20-year-old, dual pane window with something similar that’s brand new probably won’t create a large savings in energy. A modern two-pane window might have a resistance to heat flow of around R-3 and a decent triple pane might be better than R-5. A good window still makes for a lousy wall. As long as the windows aren’t damaged or falling apart, I would consider keeping the existing units. Now, you might be able to improve the air seal around the window by removing the window trim on the interior and using either a backer rod and caulk, canned spray foam, or a tape designed for window air sealing. Probably a less costly and more effective option than window replacement.
Increasing attic insulation levels is also one of the most cost-effective upgrades, but even more important is to improve the air seal between the attic/ceiling space and the home. This is easiest when the attic is a vented, unconditioned, flat ceiling design. I’m in a lot of homes that feature cathedral ceilings that were poorly air sealed when originally constructed. Correcting deficiencies in this type of roof/ceiling requires either removal of the interior finishes or the exterior roofing material to gain access to the air control layer. The thermal image shows one of the many homes I’ve found with this issue. Wood paneling and a kraft faced insulation (neither an effective air control layer) is probably all that separates the vented space of the roof from the interior. Very difficult and expensive to correct.
Standard roofs that feature a flat ceiling, vented, unconditioned attic space that uses the ceiling finish material as the location for the air barrier is an easier assembly to address. Remove or shift existing insulation to expose all penetrations (mechanical, electrical, and plumbing) leading from the conditioned space into the attic along with the top plates of the interior partition walls. Air seal the exposed ceiling and reinstall the insulation. Not very fun work, but it can make a huge difference in how the home performs. There’s a great video showing this process on The Energy Conservatory’s YouTube channel: TEC Home Performance Upgrade (youtube.com) (The air sealing process starts about 35 minutes into the video.)
Improving basement, crawlspaces and slab on grade foundation insulation and air sealing will again have many “it depends”. We covered the rim or band joist in the low hanging fruit section. Insulating basements from the interior (especially when converting a basement to living space) can be one of the more difficult details to plan. There are several articles on GBA covering basement insulation strategies.
Crawlspace improvement such as changing a vented crawlspace to an unvented/conditioned space can be a great option for improving energy consumption, comfort, and possibly indoor air quality. There are several considerations when planning a conditioned crawlspace along with many code requirements (IRC R408.3 Unvented Crawlspace) that need to be considered. The climate zone of the home along with termite risks will also dictate how the process is completed. Adding polyethylene sheeting to a dirt floor was discussed in the low hanging fruit section, converting a vented crawlspace to a conditioned space should at least have professional planning for the project.
Something I occasionally see in energy audits I perform are homes constructed prior to 2000 with in-floor heating systems that are missing slab edge insulation. Not having insulation in this area (or some insulation under the slab) in a cold and very cold climate results in very high heating costs and comfort complaints. Sometimes it is possible to add the slab edge insulation after the fact, as long as there isn’t a poured or paved surface against the foundation. If you don’t have insulation under the slab, good luck. You might be better off eliminating the in-floor heat and moving to another heat source.
- Improvements to the mechanical systems.
My rule of thumb for swapping heating and cooling systems with a more efficient system, first perform as much of #4 as possible. Decreasing the load of the home can help reduce the size requirements of any new system installed. This rule applies when making a comprehensive energy upgrade to a home. If the equipment has failed, replacement is necessary. There still may be an opportunity to resize a system or switch to a completely different system (moving from standard AC to an air source heat pump for example).
There is one exception to this rule, if a home is currently heated using fuel oil, I would consider swapping to a less expensive fuel source. Fuel oil is capable of producing more Btu’s than an equivalent amount of either propane or natural gas, but at roughly $4 per gallon in my market, plus a less efficient heating system (most fuel oil systems are 85% or less in efficiency), a smart choice might be to swap to the less expensive heat source. (Like an air source heat pump.)
My home originally had a 100,000 Btu, single stage furnace that failed spectacularly at 3am one cold, February morning. (Remember, I live in climate zone 7.) I woke to the smell of burning plastic. The failure of a safety control device in the furnace allowed it to overheat, starting a small fire. I was (and still am) in the process of improving the building envelope of my home but wasn’t far enough along to really decrease the heating system size. I chose to move from the 100,000 Btu, single stage furnace to an 80,000 Btu, two stage unit. Not only did the new furnace maintain comfort, but my natural gas bill decreased. The lesson learned; confirm the heating and/or cooling load demand for the home before simply replacing one size unit with another of equal size.
The improvements to my home.
When I purchased my 1952 Cape Cod home in 2018, I was well aware there was going to be a lot of work I was going to have to perform. The home had most of its original cladding (asbestos lap siding). The heating system (no AC) was nearing the end of its life span and eventually failed, the electric tank water heater was installed in 1990 (and it’s still in operation though I have replaced an element and thermostat). There were signs of past water damage, but the roof had been recently replaced. And then there was this thing on the north side of the home.
I knew I didn’t have an active bulk water leak from the roof, but I was pretty sure there was some water intrusion through the walls and probably also a lot of air leakage that could be causing some condensation issues in both the roof and walls. I suspected there were also ice dam issues, which were confirmed after the first winter.
Where did I choose to concentrate my initial efforts? You’ll have to wait until part 2 of this blog.