Energy Audit

A guy came through the neighborhood recently offering home energy assessments. He would do an assessment and then use that data to determine what kind of improvements could be made to increase the energy efficiency of the house, the cost being offset somewhat by Georgia Power rebates and federal tax credits. My air conditioner is over 20 years old and the furnace may well be original from 1950’s. Some of the solutions his company offers are sealing ductwork, adding insulation, and encapsulating crawlspaces, so you kind of know going in what the recommendations are going to be.

Encapsulation means they completely seal off the crawlspace. Usually you want to keep a crawlspace ventilated so that moisture and mold don’t build up, although in winter, when the air is dry, it is okay and maybe recommended to shut the vents (some vents automatically shut during cold weather). With encapsulation the house is sitting on an insulating bubble of air. To keep moisture at bay, they completely seal the dirt floor using plastic sheeting and tape and then glue the edges of the sheeting to the walls and columns. There is already a vapor barrier down of plastic sheeting, but the encapsulation is supposed to be nearly airtight. To keep the bubble of air in the crawlspace from losing heat or cooling, they insulate the inside of the exterior walls of the foundation with an inch of spray foam. Encapsulating like this can be more effective than just putting insulation between the floorboards of the house, which is sometimes recommended (I don’t have any insulation under the floor now). There may also be some amount of air conditioning or dehumidification involved in the encapsulated crawlspace. One nice side effect of encapsulation is it also keeps bugs and other critters out of the crawlspace which has been a problem in the past.

I talked to the guy some and he seemed to know what he was doing. The energy audit is pretty thorough and costs a few hundred dollars, but you can get half of it back as a rebate from Georgia Power as part of their GoodCents program. He is certified by them to do assessments, install repairs, and use Georgia Power’s Beacon software to calculate the resulting energy savings. He came out Tuesday with two technicians from a company that actually runs all of the tests. They inventoried all of my HVAC equipment, measured the square feet of the house, looked in the attic for insulation, and ended up doing a blower test where they measure how air tight the house is and even specific ducts, looking for sources of air leaks. Meanwhile the main guy went over my power and gas bills to figure out my yearly energy consumption and how much money I was spending on heating and cooling. He was surprised that I don’t really spend that much on heating and cooling. Though I gave him records for the past 8 years, he only used the last 2 and came up with about $700 per year (my calculations indicate more like $500, but last year was pretty mild and the number was higher in other years). He figured he could save me about $400 per year by getting the house more air tight, adding insulation, and upgrading the air conditioner and furnace, though usually he doesn’t do HVAC work. The total for all of this work would be about $14,000 even after over $2,000 in rebates from Georgia Power and the federal government. Neglecting the time value of money, that means it would take 35 years for me to break even. So this isn’t something that pays for itself, unlike with my refrigerator which dropped my baseline power consumption (not counting air conditioning) by 25-30% and paid for itself in a few years. However, I think I will need a new HVAC system at some point regardless, so I shouldn’t expect its cost to be paid for via energy savings.

In the overall cost of the repairs, $8,300 was for a new HVAC system which I will talk about in another post. As a standalone item, I wanted to get independent estimates on that. Another $4,000 was for crawlspace encapsulation. I like the idea of a pest-free and clean crawlspace, but eventually I realized that I could probably hire a company to make the crawlspace pest-proof for a lot less than $4,000 (and found a company that a few people in the neighborhood have used and recommend; pest-proofing the crawlspace wasn’t that expensive, but they also did the attic which got kind of expensive; but the whole thing was less than the encapsulation and the encapsulation wouldn’t have done anything about the attic). Also I wasn’t crazy about encapsulating since I’m not sure what would happen to water if it did leak in and there could potentially be problems with radon building up in a trapped air space. He also said he would seal the existing crawlspace vents with foam board which didn’t sound all that robust.

Another part of repairs was sealing the ductwork which their tests showed leaked anywhere from significantly to amazingly. He gave me estimates for either sealing the ductwork ($1,500) or replacing all of the ductwork ($2,100). However, my HVAC guys said he could replace all of the ductwork with insulated lines (only the air leaving the furnace has insulation now, not the returns) for a little less. He also said that old houses like mine were built with the vents on the inside walls of the house and return registers were on the exterior walls. Now the practice is to do the opposite. I thought that if I was replacing the ductwork anyway, maybe I could go with the new scheme, but I would also need to change the registers out which is harder than it sounds. I’m not even sure there is an advantage to changing the layout, but there must be something if that’s the way it is done now.

This was leaving very little work for the original guy to do. But the only way I could get some substantial rebates from Georgia Power was if he could certify that I was saving 20, 25, or 30% in energy (for rebates of $1250, $1450, or $1850 respectively). So if I cut him out completely, I can’t get it certified because most HVAC installers aren’t looking at the entire energy situation and aren’t certified by Georgia Power to make the determination using tests and the software. Now I am thinking I will still have him do some work in the attic adding insulation, replacing my attic stairs which don’t close properly, and setting up seals over the house fan and attic steps which are sources of air leaks, along with sealing a door I installed badly and my ash dump which is just a metal door in the back of my chimney that doesn’t shut all the way. Those things will all help show an improvement in overall house air leakage that should help my energy reduction score. 30% would have been easier to obtain before I replaced my refrigerator with a way more efficient one and all of my light bulbs with compact fluorescents. The program would be great for an old house with very few improvements already made, but I think I can still get to 20% (looks like maybe 25% [edit: wound up with 30% anyway]).

I talked to the guy today about my plan to slash his services and give him a chance to revise his prices on the remaining work since I’m sure much of the profit was in items being eliminated. He wasn’t crazy about the cuts and wants to try to come up with a HVAC system that will beat the one I found on my own. I told him I was thinking about paying $2,000 more for a variable speed two-stage HVAC system with a fancy wi-fi thermostat, but he said I would be better off putting that money towards the encapsulation, which, along with all the other recommendations, would get me to 30%. Also he pointed out that part of the test for energy efficiency is based on the air ducts being pretty tight and if my contractor leaves leaks, I will have to get him back on the site and then pay for yet another test of the ducts to see if they pass. So it might be better for him to do the ductwork if the price is about the same and then he can make fixes if the ductwork doesn’t pass. However, if I ever have problems with the HVAC, I don’t want them to be able to blame the ductwork.

I can monitor the energy savings over the next year or so and then decide later if I want to do the encapsulation. Small improvements are very hard to track because a mild winter or summer throws the overall energy consumption numbers off a good bit from one year to the next. While I can always do encapsulation later, I can’t add SEERs or cooling stages to the HVAC system later without replacing it entirely.

This work could start up as early as next week along with another project to replace my gutters and repair some damage from gutter leaks and squirrels.

Leave a Reply

Your email address will not be published. Required fields are marked *