What Would a “Pretty Good House” Look Like? Part 1.
What is it about Maine? Some of my favorite people in the home energy pro community live there. We just signed up our first HERS Rater from the state (Diane Milliken of Horizon Residential Energy Services). Now, some folks there who meet monthly to talk all things green building have come up with a an enticing new concept: The Pretty Good House. This could be the next big thing!
Because each of the existing green building and energy efficiency programs has flaws, they started discussing the question, What would a Pretty Good House look like? Dan Kolbert facilitated the discussion, and Michael Maines wrote it up at Green Building Advisor (links below). In the first article, they came up with a list of items to include and another list of things to exclude. In the second article, they expanded on some of the ideas and included some new ones.
What’s the question again?
Even before I actually read the first article, I started thinking about what a Pretty Good House might look like. Since I’m in International Energy Conservation Code (IECC) Climate Zone 3, my thoughts naturally gravitated to elements that would work well in a mixed-humid climate: Building envelope details, right-sized heating and cooling systems, ducts inside the envelope, mechanical ventilation, ceiling fans…
But then I took a step back and asked the question, Whose Pretty Good House are we talking about here? You have to ask that because my Pretty Good House would probably look different from the Pretty Good House of someone who’s in the trenches building custom homes. The disparity would be even greater between my Pretty Good Home and that of a production home builder.
Since it’s the Pretty Good House, I’m going to take the view that even production builders should be able to achieve it…if they really want to and work hard to do it. Because it’s voluntary, it should be better than the worst house allowed by law, i.e., the code-built house. With the code getting so much tougher in the 2012 and 2015 IECC versions, that latter objective gets harder and harder to do.
The Pretty Good House in a mixed-humid climate
If I had my own Pretty Good House program here in the climate zone 3, here’s some of what I would want to see:
Pretty Good Design
The Pretty Good House must begin with design. This is where you have to start to make sure that the building envelope, water management systems, and mechanical systems get integrated properly. By the end of the design phase, everyone would know where all the ducts, wires, plumbing pipes, insulation, air barrier, and flashing details are going to go, what materials they’ll use, and when they’re getting done.
Design review. All the critical team members review the plan and strive to minimize surprises once construction starts.
Complete HVAC design. Before the foundation is built, the HVAC contractor knows what the heating and cooling loads are, which system is going in, and all of the distribution details.
Projected Home Energy Rating. Along with the HVAC design, a HERS rater works up the preliminary HERS rating.
Pretty Good Site
When possible, the building site should be oriented properly to allow for passive heating and cooling. Whatever the site, though, there needs to be a plan to deal with all the erosion, tree protection, orientation, and other site-related issues.
Pretty Good Building Envelope
In this part of the Pretty Good House, it’s going to be hard to improve upon the 2012 IECC, so I’d go with their insulation levels. The building envelope also must be complete and continuous, of course. The insulation and air barrier must be in contact with each other and use materials that will stay in contact with each other for the life of the assemblies (i.e., no batt insulation in framed floors).
Other goodies:
Blower Door testing. 0.25 cfm per square
foot of building envelope (or 3 air changes per hour, if you must) at 50 Pascals. Joe Lstiburek says this is a pretty good air leakage threshold for homes.
Grade I insulation installation. No exceptions. It’s got to be done right. ENERGY STAR may have backed off of this a bit since I wrote about it earlier, but that doesn’t mean we should.
Reduced thermal bridging. Foam board on the outside, structural insulated panels, insulated concrete forms, double wall construction, or some other method that would produce a nice, uniform color when someone looks at the house with a thermal imaging camera.
No big or medium holes in air barrier or insulation. The Blower Door test will catch the air barrier holes. Thermal imaging and third-party inspections will catch the insulation holes. Some places to watch out for are attic access holes, slab perimeters (must be insulated for CZ 3), ceiling insulation above exterior walls,
I’m thinking that the shift in the IECC from R-values to U-values, as Wes Riley pointed out in the second Pretty Good House article by Maines, can lead to better ways to view the house. In fact, since size matters so much, let’s go even further and look at levels of performance based on the UA values.
Pretty Good Heating & Cooling
As I said above, each Pretty Good House would get complete HVAC design up front. I’d also want:
> 1000 square feet per ton of air conditioning capacity. This is my rule of thumb, and I think it would be a nice way to make it easy to check. If it were my house, I’d want no less than 2000 sf/ton, but remember, this is the Pretty Good House, and that’s a pretty good benchmark.
All distribution inside the envelope. No ducts in attics especially. Crawl spaces get encapsulated.
No atmospheric combustion. If it’s not electric (e.g., heat pump), it’s got to be sealed combustion. Period. You can’t call it a pretty good house otherwise.
That’s a pretty good start.
I’m sure I didn’t get everything related to those topics in there that should be there. I’ll post again about this topic and cover the items below that didn’t make it into this already-long article.
In Part 2, I’ll cover:
- Pretty Good Verification
- Pretty Good Performance
- Pretty Good Water Heating
- Pretty Good Water Management
- Pretty Good Water Conservation
- Pretty Good Homeowner Package
I’m sure I’ll have some clarifications and refinements based on the comments you’re going to leave me, too, so go ahead and start typing now.
The Green Building Advisor Posts on the Pretty Good House
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I strongly feel we at
I strongly feel we at ThermaSteel Wall System have the BEST envelope for any region if the USA or even the world. The attic will be the same temperature as the first floor. The HVAC system is engineered for the size and humidity is controlled. The hot water system is outside the home. I built a custom home like this last year. I am looking for the best HVAC system for the new custom home I will be building for a client – but the structure of the walls and roof, just can’t be beat!
It’s all really about payback
It’s all really about payback time for energy investments. The ‘pretty good house’ looks a like a good balance of performance vs. cost. Grab the low hanging fruit for quick payback time.
By offering single piece
By offering single piece corner panels with a dense polyurethane (not the cheap EPS) foam core, Eco-Panels of North Carolina offers the only continuously insulated structural (SIP) building envelope on the market today. In this time of increased tornado activity one of the weakest parts of a home is where two walls come together – and we have entirely eliminated that weak joint. Exterior siding skins can be lapped down over the rim joist or up into the second floor or roof trusses, creating a significantly stronger, safer and more energy efficient home.
Janet Farr, the envelope
Janet Farr, the envelope system you refer to sounds almost magic. Under what circumstances can the envelope assure temperature being equal from top to bottom of the structure. This would be worthy of an entire blog essay describing it.
Once again… Maine. It seems
Once again… Maine. It seems like no one west of the Big Muddy is working on house insulation. Is there anyone in HERS that works out in the arid and semi-desert areas?
Looks pretty good so far
Looks pretty good so far Allison : )
I had to do a similar presentation lately & one thing I pushed was doing two layers of foam outside. i.e. if you want 1″ of foam – 2 layers of 1/2″ offset to eliminate expansion & contraction issues
John there are plenty of guys out there & many can be found on http://homeenergypros.lbl.gov/ – but if you got a general question lets here it as I spent 30+ years in Arizona
We are doing lots of this
We are doing lots of this west of the Big Muddy too.
Our targets are “Pretty Good” as well. It has to be a sensible mix of features. In the end it all boils down to “what works that is simple and durable.”
One thing I like about insulation is that it lasts forever! Smaller AC equipment costs less, and I would add to that when sized properly as in 1000-2000 sq ft a ton it does not need to have all the fancy multi-speed features that can break down a lot. Our targets for sizing AC are the same, even in the harsh desert climate where it gets 115 degrees out – the pretty good shell makes that possible. In other words – the plain simple AC equipment “Right Sized” is pretty good.
I think you will find that the comfort, health and durability of those pretty good homes will be fantastic and well beyond the average of the status quo of typically thought to be pretty good homes.
Janet F.:
Janet F.: This article isn’t about specific products. Please comment on the points in the article and don’t just post advertisements for products you sell.
Bob: True. But it’s not all about payback. The Pretty Good House also is comfortable, durable, healthful, and good for the environment.
Charles L.: See my comment to Janet above.
M. Johnson: Indeed!
John M.: See Sean’s comment right below yours.
Sean L.: Two layers of 1/2″ foam outperform a single layer of 1″ foam. Joe Lstiburek found the single layer of foam to be one of the problems when he had to redo his deep energy retrofit last year.
Chris C.: Well, some insulation lasts forever. Fiberglass batts installed in framed floors or attic kneewalls with attic-side sheathing tend to fall out pretty quickly.
Allison
Allison
Since I am in the business, I whole heartedly agree with you, but that wouldn’t make for good conversation.
So as devil’s advocate, from a consumer or builders perspective, wouldn’t this be a “Very Good” House?
Wouldn’t this bring the costs of building the home up significantly?
Aren’t these “pretty good” demands bordering on reaching the v3 Energy Star specs that builders are already grumbling about?
Finally, the ultimate question….How are you going to get people to adopt something that makes total sense in a world that follows the “we been doing it this way for 20 years, if it ain’t broke, don’t fix it” mentality?
Since I have focused more on the retrofit side, I believe there is a “Pretty Good House” approach on that side as well. Usually this concept is driven by budget constraints. For instance, I have advised (and been criticized for) home owners in the past that were looking to install a 16 SEER unit to instead opt for a 13SEER unit and spend the extra $3000 on improving the air sealing and insulation so they weren’t just more efficiently losing/gaining heat. In the end, the overall results are “pretty good” and they stayed within their budgets constraints. Do you think this is a reasonable approach?
Thanks for the links to the GBA articles and great article as always. Jon
Looks good from the outside,
Looks good from the outside, something about that double porch.
We have developed low a cost drainpipe heat exchanger (see web site above) for waste heat recovery which can always add significantly to the savings.
This is a good start, but I
This is a good start, but I agree with others that have posted on the article. In the end everything we do at Lifetime Structures is about payback on the investment and is driven by simulation modelling, pre-construction design, system optimization and post construction verification. We look to spend our next dollar on every project to saving the most amount of energy and it has served us well. Comfort,health and customization are always a given, and rarely cost more if designed properly.
The proper construction of
The proper construction of the building envelope is key in my thinking. “Big or medium holes in the air barrier and envelope” are easy and not too costly to address but some, like the uninsulated slab edges mentioned above, have been either ignored or improperly installed by the “we been doin’ it this way for 20 years” group mentioned by Allison. This one detail, exposed concrete perimeters, accounts for 10% – 20% of the total heat lost from a medium size home. (Code requires SEI in Zones 4 and above.)
IMHO cost effective payback
IMHO cost effective payback is when utility bills are decreased by more than the house payment increase.
Bob, Great point! Your
Bob, Great point! Your comment on payback brings up a pet-peeve of mine… Some contractors in working for a client to “value engineer” really wind up only “cost cutting”. Big difference! Many value added products and solutions are cut during this process.
To meet necessary carbon
To meet necessary carbon reduction targets, we now need to be reducing energy usage by something around 5% per year, year after year. (Remember that energy savings compound backwards, too.)
When pegging the energy usage of the pretty good house – that’s going to be built in the next year or two, say – what year should provide the performance target?
This translates to the degree of planned energy obsolescence, unless the target year is way out there. Do we want to build something now that we can predict will need a difficult retrofit in just 20 years? 30 years? When?
Good info
Good info
Maine Green Building Supply
Maine Green Building Supply is the home of the original Building Science Discussion Group and this is where we first discussed this concept. We have started a PGH blog on our site and welcome comments and suggestions. (http://www.mainegreenbuilding.com/blog/pretty-good-house/pretty-good-house-list/)
Before becoming a Hers Rater
Before becoming a Hers Rater I took a tour of a ICF house a guy built for his Home Business. He had a Recording studio next to a very busy/noisy highway. His solution was to put double pane windows on the outside of the building with additional set on the inside. This created a 12 inch dead air space between the two sets of windows. The effect was dramatic. I have never been in any space that quiet before or since. I’m wondering what kind of numbers could be attained with this approach compared to one set of triple pane windows.
Considering extra labor costs V.S. lower window cost and ease of finding/installing double Pane windows compared with triple. Weigh this against the added performance of a double assembly. Any thoughts?
This looks…pretty good! Ha.
This looks…pretty good! Ha.
Gotta agree with Winston, I love that double porch! Looking forward to reading the follow up posts on this one.