Archive for September, 2010
How Much Green Is Too Green?
Wednesday, September 22nd, 2010So, you spend $140,000 on a deep energy renovation (DER) and, after a few years of doing the calculations, discover that you’re saving $2,000 a year on energy costs. Was that a good investment? This was a scenerio posed in the November 2010 issue (#214) of Fine Home Building. It begs the question, just how green is green enough, and what metrics should we be using to decide? When I posed that question as a discussion topic to a young contractor, he pooh-poohed the question as too easy and quipped: That’s up to the individual.
Truly. But that doesn’t mean “the individual” has the knowledge and expertise to make informed decisions.
Some time before I started this website I was called out to a lovely house that a couple had just purchased. It was a sprawling ranch style home built shortly after the end of the War. But whom-ever designed it was obviously not from Earth, since they thought the afternoon sun in the northern hemisphere was to be found in the Northeast. That’s where the sun room was located. It was a lovely sunken room with some of the biggest plate glass windows you ever saw set in redwood posts, two sets of hand made double doors also set with thick plate glass, and a natural stone floor that had been polished smooth. There were two double wide entrances to this lovely room. One from the formal living room and the other from the kitchen.
The lady of the house called me because, even though her new home sat on top of a sunny hill, her heating bill was $500 a month. And that was in the summer time! In the winter it topped $1,000. She and her husband had already dumped over $20,000 into a new kitchen before even moving into the house and, after reading about double pained windows and the efficacy of insulation were afraid they were going to have to do a very expensive DER, a message three other contractors had confirmed. Something they just couldn’t afford.
After a quick walk around, snooping here and there, I put the brakes on the whole DER idea. There were just too many other problems that needed to be addressed first, before ripping off siding, tearing into walls, and making that oh-so-fun walk down window lane at the hardware store.
That sun room was high on my hit list. It didn’t take thermal imaging to realize that it was a major heat sink—or, more accurately, cold sink. Being in the Northeast, it was cold even in the heat of summer—which was when I inspected the house. There was probably a ton of plate glass in that room, and you could see daylight under the thresholds of the double doors. In fact, you could see daylight under all the outer doors except the main entrance, which had obviously been changed. The furnace was original equipment. When it was installed, natural gas probably cost a half-cent per cubic foot. And of course, there was no insulation anywhere.
After letting the homeowner wind down while I inspected things, I sat her down with a pencil and paper and had her make out a list:
- Weather seal all the external doors and repair the thresholds and door sweeps as necessary.
- Install insulated curtains around the sun room. (A trick I learned from my mom who had a similar problem with big old plate glass windows.) In the winter time, close the living room and dining room doors to the sun room. In fact, weather seal them too, to help create a more complete barrier.
- Insulate the attic.
- Pitch that old furnace out into the street and replace it with a new Energy Star model. And make sure the HVAC contractor re-seals and insulates all the duct work. If they find duct work that’s bad, replace it. In fact, I sent them to my preferred HVAC trade contractor because I knew he’d treat them fairly and do a good job.
I made no money on that job. The husband of the house was rather handy, so everything but the new furnace was well within his ability. Nor do I know exactly how much they ended up spending. My estimate was less than $10,000. I did learn that the work reduced their energy bills by about 68%, and the cost of the work was paid off in energy savings in less than two years.
If you’ve been reading along here for awhile, you might remember that one of the first articles I posted was about life cycle costing. In that article I talked about something called Q*: The optimal point where energy savings and the cost of the work to achieve those savings, plus the maintenance cost over the long haul (the life cycle cost, or LLC), meet. Q* is, therefore, an economic calculation that may not serve the interests of those whose primary goal is not maximizing economic efficiency, but rather environmental impact. But for those who are seeking maximum impact for their dollars, Q* is absolutely critical, if very hard for a layman (and even many contractors) to compute.
Moving from the far left edge of the graph above to as close to Q* as I could get without breaking their budget was my (informal) goal as I analyzed the house and provided guidance to this particular family. Did we reach Q*? I certainly moved the needle, but I doubt we got very close. To be honest, I didn’t do the math. I didn’t have the actual numbers with which to do the calculations even had I wanted to. But I think I came closer, if on the left side of the graph, than the over-kill in the first example did on the right side of the graph. Even adjusting for inflation, the folks who dumped $140,000 into their DER will take 44 years get their money back.
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