Replies

1. GBA Editor
   Martin Holladay | Dec 10, 2009 10:16am | #1

   Rob,
   The DOE's low-income weatherization program has decades of experience prioritizing energy retrofit work. If you are not familiar with the program, I suggest you get in touch with your local weatherization agency to tap into their expertise and inquire about their software programs.

   Most RESNET-certified HERS raters or BPI-certified energy auditors should be able to help you prioritize energy retrofit options so that the work with the greatest energy payback comes to the top of the list.

   Needless to say, health and safety concerns always trump energy concerns.

2. 
   Rob Moody | Dec 10, 2009 12:06pm | #2

   Thanks Martin. I am familiar with WAP and I'm a HERS rater. According to some experts (including Michael Blasnik which I blogged about here, here and here) the computer models are oftentimes inaccurate. It seems that TREAT and RESNET both underestimate cooling and overestimate heating for certain climates. Furthermore, with such a small budget for some of these projects, the highest SIR may be for strategies such as refrigerator replacement. It would be hard to take a hardline there and replace an inefficient fridge when the windows are leaky as hell, there is no insulation and no heat.

   I know that you can't make the cake and eat it too, and I may be worrying too much about the inadequacies of the modeling software.

   Here's an example. One project home has no heat source, inefficient window ACs, sloppy R-19 insulation in the attic, an inefficient fridge and the windows are literally falling apart. The budget is roughly $5000. I don't believe the REMRATE has been calculated yet, but it will be through the roof. I hate to think about opening the wall cavity from the outside, air sealing and not insulating because the budget is not there. But that may be what we have to do. The Curmudgeon is convinced that in humid climates, adding insulation to existing wall assemblies that are vulnerable to bulk moisture is a case for disaster anyway, so maybe this strategy makes since. We will be running this through REMRATE and UCLA's HEED (Home Energy Efficient Design) as well to get a model for evaluation.

3. GBA Editor
   Martin Holladay | Dec 10, 2009 12:18pm | #3

   Rob,
   As you probably know, it is sometimes necessary for the low-income weatherization program to tell homeowners, "You have a structural problem here that is beyond our ability to address. We can't perform weatherization work until this structural problem is fixed."

   Another example: if a crawl space is subject to regular flooding (say, due to proximity to a river), and the crawl space has 8 inches of water when the weatherization crew arrives, then nobody's going to start air sealing and insulating the crawl space.

   I'm not sure the scope of your program. But if you have buildings with no heat source and windows that are falling apart, major decisions have to be made. What's the budget? What's the aim of the program? You can't make energy efficiency investments in a house that is falling apart.

   There's nothing wrong with addressing basic needs in a house, even if the work doesn't have an energy payback -- as long as you have the budget. There's no reason to insulate a cathedral ceiling if the roof is leaking. In such cases, common sense is more useful than energy modeling software.

4. 
   Robert Riversong | Dec 10, 2009 12:29pm | #4

   "I know that you can't make the cake and eat it too"

   Actually you can, and almost always do. What is the purpose of making a cake if not to eat it?

   And the more common permutation - "You can't have your cake and eat it too." - is similarly absurd.

   What we mean is that "You can't eat your cake and have it too." Once the money is spent, however wisely or foolishly, it's gone.

   Air sealing and a working direct-vent heater are the basics. The first, the most cost-effective. The latter, the most essential.

5. 
   Rob Moody | Dec 10, 2009 04:49pm | #5

   Thanks for the clarification. I was in a hurry and fell into that trap. I guess if you are a commercial baker, you don't eat most of the cakes that you bake.

   Anybody think that the single direct vent could be somewhat distributed by an ERV? I am thinking about locating the inside return near the heater and the inside supply at the farthest point from the heater.

6. 
   Robert Riversong | Dec 10, 2009 06:11pm | #6

   "I am thinking about locating the inside return near the heater and the inside supply at the farthest point from the heater."

   That my work for moving heat around, as long as all doors have a minimum of 1" airspace underneath or there are transfer grills over doors, and as long as that pathway scours the entire living space.

   But does it adequately remove moisture and pollutants and distribute fresh air to all bedrooms and living spaces?

7. 
   homedesign | Dec 11, 2009 07:28am | #7

   ERV???
   Rob,
   I am surprised you are considering an ERV or HRV in a poor performing home.
   It is hard to justify the "payback" in a high performance home.
   Agreed that you need a strategy to distribute heat if you use a single heater...
   But ERV??

8. 
   Rob Moody | Dec 11, 2009 08:15am | #8

   In response to Robert above, there will be AC window units for dehumidification and the ERV will have a two way inlet/outlet for fresh air introduction.

   In response to John, the home is to mitigate the energy penalty of the ERV with insulation upgrades. I'm trying to balance the budget by creatively using the single point heat system so we can afford wall and attic insulation.

   I am fully aware that I am being somewhat Utopian in my aspirations. It is a struggle to try to provide all of the things that we know the family needs in this home. It is a difficult living situation and a huge challenge to reconcile best practices with the minimal budget. I want to meet that challenge in some way. Obviously, the first order of business is to do no harm. Important to note, the budget is leveraged by the fact that this program has a workforce paid out of a different budget, essentially providing free labor for the non-MEP work.

9. 
   MICHAEL CHANDLER | Dec 11, 2009 06:23pm | #9

   I think the cost of the ERV would not be a good use of limited funds here in that the house is already over ventilated and the work that fits within the budget will likely not be enough to get it tight enough to make the ERV worthwhile.

   I would also not make insulating walls a top priority because to protect the insulation from water you would need to improve flashings and siding and to install a drainage plane (likely absent) at which point you'd probably also want to replace windows and doors. Insulating walls in old mill houses is a slippery slope to a blown budget. Self_help here in Durham poured Demelec into walls in a bunch of old mill houses here in Durham a few years back and created a huge list of un-intended water retention related problems. With-out a drainage plane you are asking for trouble to add insulation. Its much easier to seal the crawl and the ceiling plane and look for other less expensive "low hanging fruit".

   So I'd start with putting that free labor to use draft sealing the exterior siding, windows and doors and the floor and ceiling planes. Then confirm that there are no wiring, plumbing, or other infrastructure issues in the attic and bury the ceiling in as much cellulose as you could fit without restricting the air flow under the roof. After that I'd put plastic down on the floor of the crawl and seal the exterior walls with a double layer of 1" XPS with offset joints, leaving a termite inspection gap if you are in, or near, a termite area.

   I like the idea of the single, sealed combustion gas heater and I'm thinking that the clientele you are talking about would be able to tolerate some chilly nights in the bedrooms or else sleep with the bedroom doors open if the trade off was better insulation overhead and lower energy bills. High and low transfer grilles might also be worth experimenting with if the sound transfer isn't a problem.

   For ventilation I would replace the bath fans with durable Energy Star rated fans and put them on time delay motion sensors to enforce their use.

   I'd also create a good home-owners manual to educate the clientele about energy and water conservation and especially about combustion safety and carbon monoxide poisoning. I'd put in at least one carbon monoxide sensor and I think it's worth the extra cash to use CO and smoke detectors with ten year batteries. These are small homes and probably will only need two to three detectors so the up-charge is minimal. I'm using the Kidde Silhouette model and am very satisfied.

   Finally I'd insulate the water heater and hot water pipes and confirm that all open flame appliances have been isolated from the living space or replaced. State makes a pretty decent closed combustion tank style gas water heater w/ concentric piping but I'm assuming that most of these homes will have electric water heaters and with this budget that's probably not worth changing other than to add insulation. And yes, get rid of the old fridge (remove and destroy so it doesn't see "adaptive re-use" as a kegerator).

   Sounds like a great project, we need to focus on this type of work for all types of housing and light commercial, not just the low-income mill houses, though that's a great place to train the workers we'll need to go after the rest of the energy hogs across the country.