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The Pretty Good House

Finding the right balance between construction cost and energy performance

Posted on Feb 6 2012 by Michael Maines

Energy Star. LEED. Passivhaus. There are many programs with different metrics for determining how green your home is. But what elements of green building are important to you when designing and building a home?

This was the topic recently at our building science discussion group. (For more information on this group, see Dan Kolbert’s article in this month’s JLC, “Pros Benefit from Building Science Discussion Group,” and my blog, “Steve’s Garage.”) The topic is something Kolbert has been thinking about for some time. There are issues with any “official” program — many in the green building world believe that Energy Star requirements don’t go far enough; LEED is comprehensive but expensive to administer, run by a private company, and it seems to be possible to get around true sustainability in the pursuit of points; Passivhaus is the gold standard for energy use, but puts no weight on other aspects of green building, some consider it too extreme, and it is currently embroiled in political in-fighting.

So, along the lines of Sarah Susanka’s “Not So Big House,” Kolbert asks the group, “What would a Pretty Good House look like?”

Local materials, plenty of insulation, and not many square feet

The discussion group is a mix of people from many professions and backgrounds, so asking for consensus would normally be a joke. In this case, however, there seemed to be an unusual lack of argument that one could almost take for agreement.

In no particular order, we determined that a Pretty Good House should:

  • Support the local economy. That means building with local labor, with locally available and/or produced materials, as much as possible.
  • Be commissioned following construction, and be monitored on an ongoing basis. If you don’t know, and to me it’s a strange use of the word, commissioning means testing how the house performs after it’s built. There was some discussion about how effective an energy-use “dashboard” can be. (“What gets measured gets improved.”)
  • Have operating costs that are minimal or reasonable.
  • Have 10-20-40-60 insulation. Hopefully these numbers are obvious: they represent a “pretty good” level of insulation in a cold climate for sub-slab, foundation walls, framed walls, and roof or ceiling, respectively.
  • Measure 1000-1500-1750-1875. These number are probably not as obvious; they represent an allotment of square feet of living space for 1, 2, 3, and 4+ inhabitants, respectively. It could be less — the national average is much more — but as a group we thought this was… pretty good.

What's in and what's out?

We came up with a list of what is in versus what is out of a pretty good house. What's in:

  • Superinsulation.
  • 4 inches of rigid foam under the basement slab.
  • A service core for plumbing and wiring (à la Tedd Benson’s Bensonwood concept, also a feature of A Pattern Language (Alexandar, et. al.): keep services out of exterior walls, grouped for easy upgrades in the future.
  • Energy modeling (performed during the design process).
  • Adaptability/durability/recyclability. For more on this topic, see Alex Wilson’s blog, “Ensure Durability and Reuse Existing Buildings.”
  • An air leakage rate of no more than 2 ach50. Not exactly Passivhaus, but… pretty good.
  • Good design. I was surprised it took so long for someone to mention this. A good house has to look good and feel good, not just function well.
  • An owners’ manual. I know that Michael Chandler has written about this. You get an owners’ manual with your car, DVD player, and electric toothbrush. Shouldn’t the biggest, most expensive, most complicated thing you own have an owners’ manual too?
  • Universal Design. Our population is getting older, and people are realizing that having a disability does not mean one's lifestyle needs to be limited. For the most part, Universal Design is smart design.
  • Comfort. Recently I was at Chris Corson’s Passivhaus project on a cold day. There were no drafts, no cold spots in front of windows, and only a single Mr. Slim heat pumpHeating and cooling system in which specialized refrigerant fluid in a sealed system is alternately evaporated and condensed, changing its state from liquid to vapor by altering its pressure; this phase change allows heat to be transferred into or out of the house. See air-source heat pump and ground-source heat pump. for the whole house. It was comfortable. I’ve been in $20 million dollar houses that were not comfortable (and probably insulated with fiberglass batts).

Keep it simple

What's out:

  • Passivhaus under-slab insulation. 10 to 14 inches of foam? As great as many of us think the Passivhaus standard is, it’s still hard to imagine using that much foam under the slab.
  • Toxic/unhealthy materials. Duh.
  • Too much embodied energyEnergy that goes into making a product; includes energy required for growth, extraction, and transportation of the raw material as well as manufacture, packaging, and transportation of the finished product. Embodied energy is often used to measure ecological cost.. Spray foam is a great insulator, but it comes at a cost. VinylCommon term for polyvinyl chloride (PVC). In chemistry, vinyl refers to a carbon-and-hydrogen group (H2C=CH–) that attaches to another functional group, such as chlorine (vinyl chloride) or acetate (vinyl acetate). siding is cheap and (somewhat) effective, but it comes at a cost. Bamboo flooring comes at a (transportation) cost, and having installed quite a bit of it, I don’t think it’s all that great….
  • Diminished returns. The idea of the Pretty Good House is to find the sweet spot between expenditures and gains. When is enough insulation enough?
  • Complexity of structure. With modern living space “needs” and small lots come oversize houses. One way to reduce the apparent scale of the house is to chop up the roof with dormers, pepper the walls with bumpouts, and otherwise create places for ice dams, air leaks and extra construction labor and materials (see Martin’s blog, “Martin’s Ten Rules of Roof Design”). I’m guilty of frequently designing in dormers to the renovations and additions I work on, as a way to buy extra space while respecting the original architecture…but at least I’m aware that it’s a problem.

Sometime soon we'll revisit this at our discussion group. What would you include in a Pretty Good House?


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Image Credits:

  1. Diane Milliken

101.
Feb 20, 2012 11:34 AM ET

Scandinavians
by Peter Hastings 4C

Martin,
I'm sure you're right that social equity would be part of the appeal of Green Building for many Scandinavians. I don't think that undermines my premise that it will only be possible to persuade the bulk of the Western World to act responsibly and equitably if neither of those words appears in the sales pitch. Even the suggestion that they are being rationed or are helping the less-advantaged will be sufficient to sink any program.
The good folks of GBA (who prove time and again that they are rational, responsible and equitable in their outlook) are an exceptional minority. Significant action will require an appeal to the masses - however distasteful the idea of involving Madison Avenue may be to some of us.


102.
Feb 20, 2012 11:46 AM ET

Response to Peter Hastings
by Martin Holladay

Peter,
You might be right -- but you're a hard-boiled cynic, that's for sure: "Even the suggestion that they ... are helping the less-advantaged will be sufficient to sink any program."

Has it come to this? The concept of helping the less advantaged is a poison pill?


103.
Feb 20, 2012 5:43 PM ET

equity and the PGH
by Michael Horowitz

Many programs including PHPP, LEED, and Energy Star, BREEAM, use the word "sustainable" in their marketing material. "Sustainable" implies, at the very least. generational equity. Most definitions include social equity.

We are already building green-er. We should also be striving for a building industry that truly addresses sustainability. We need to leave an extra star or points at the top to accommodate that excellence and humility. Others will emulate.

Am I idealistic? Just look at PHPP for what it has brought us. Who thought 20 years ago they would see a home with R-60 walls and an R-90 roof that could be heated with a 1500 watt heating element? Ok some of you can put your hands down. People look to standards to tell them what is green or sustainable or enough. And those standards are referenced, That is part of their purpose. And since I believe that sustainability IS about size and quantity and fair share, I actually think this pretty good house, done right, can be part of that trend toward sustainable building. Humble.

And Albert, with all due respect (I really liked what you said), I think that if "energy efficacy" was promoted it could lead us to building methods as I have said, that maintain a benchmark of energy per capita (like the 2000W society), and therefore lead us into a more sustainable future. The PHPP program wouldn't actually look much different if it was geared to energy efficacy - there would be a requirement of site generation in a direction toward net zero until the energy/occupant benchmark was met. The energy equity house. Philanthropy in housing.

Some people do need to be told that 10,000ft2 is not green. http://www.prnewswire.com/news-releases/one-of-the-greenest-luxury-homes... The folks at LEED for example.


104.
Feb 20, 2012 8:04 PM ET

Edited Feb 20, 2012 8:05 PM ET.

You're exaggerating
by Dan Kolbert

It's only 9800 sf.


105.
Feb 21, 2012 9:15 AM ET

But they have PV panels
by Michael Maines

Four PV panels power the home's six refrigerators.

Oh, I see... the house is on a golf course. By "Green" they mean putting green.


106.
Feb 21, 2012 9:44 AM ET

What a fun news release
by Martin Holladay

There are so many ways this home is green. It has artificial logs made out of a composite product -- so that has to be better than real logs, right? No trees were hurt when these logs were manufactured.

And I'm sure that the state-of-the-art media room has a very small TV, right? Oh, it doesn't? It's really rather big, you say?

How about the wine cellar? Maybe the wines are all organic wines from local wineries. That would help, right?


107.
Feb 21, 2012 9:02 PM ET

restraint
by Michael Horowitz

I am sure if it weren't for their guiding green principles this home would have been much bigger with perhaps his and hers media rooms, clubbed baby seal rugs, old growth redwood siding, and a snow melt system for the entire premises.

It's not what they DID that made this house green, but what they DIDN'T do..Thank goodness someone is willing to show restraint.

All in the name of sustainability.


108.
Feb 21, 2012 9:24 PM ET

The more you spend...
by Dan Kolbert

The more you save.


109.
Feb 22, 2012 11:57 PM ET

Edited Feb 22, 2012 11:59 PM ET.

Oregon's study
by Michael Horowitz

Oregon's Department of Environmental Quality did an extensive study on reducing waste (including wasted energy) in housing stock. Below are bullets directly from their executive summary- http://www.deq.state.or.us/lq/pubs/docs/sw/ResidentialBldgLCAExecSummary...

• Reducing home size is among the best tier of options for reducing waste generation in the Oregon housing sector, while simultaneously achieving a large environmental benefit across many categories of impact. Increased density and fewer home possessions were not explicitly included in the scope of this study and could further contribute to the benefit of small homes;
• Policies that reverse the trend in increasing house size would be extremely beneficial for both waste prevention and a broad range of environmental impacts and even modest decreases in home size are likely to produce important environmental outcomes;
• Families who choose or require more living space may mitigate a larger home’s impact by adding green building practices. The relationship between home size and environmental impacts suggests that larger homes be held to a more stringent building standard;
• Reduction in home size is a significant leverage point for impact reduction and may be a more effective measure than achieving minimum levels of “green certification;


110.
Feb 24, 2012 8:39 AM ET

Tie in with Ann's blog
by Dan Kolbert

I think Ann Edminster's current blog on team integration - http://www.greenbuildingadvisor.com/blogs/dept/guest-blogs/high-performa... - is also part of the solution. Many problems we currently solve by throwing SF at them could probably be solved by the team (owner-designer-builder) thinking things thru better from the start.


111.
Mar 9, 2012 12:03 AM ET

Holding myself back saving
by aj builder, Upstate NY Zone 6a

Holding myself back

saving wear and tear on my puter


112.
Aug 15, 2013 2:36 PM ET

Pretty Good House - suggestions
by Charles Herrick

(1) mud rooms
(2) double-portal entries
(3) wrap-around porch overhangs (to shield the walls from the sun)
(4) radiant barriers in the roof and even the walls
(5) landscaping with deciduous trees for shade
(6) don't put doors and windows on the west or south sides of structures
(7) put free-standing auxiliary cooling and heating systems in problematic rooms and in spaces that are the farthest from HVAC systems


113.
Aug 15, 2013 2:51 PM ET

Oregon's Study
by Charles Herrick

Follow up to Michael Horowitz: Good grief. Is this what passes for government spending of our tax dollars these days? Given a suite of technical issues, the State of Oregon suggests ... wait for it ... building less of a house? Did these so-called engineers release this study with a straight face? Seriously?


114.
Aug 15, 2013 3:08 PM ET

Response to Charles Herrick
by Martin Holladay

Charles,
Your recommendations seem to apply mostly to hot-climate houses in the Northern hemisphere. Your advice, "Don't put ... windows on the ....south sides of structures" may make sense in Tierra del Fuego and Florida, but it doesn't make sense in Vermont.


115.
Aug 16, 2013 10:49 AM ET

Response to Martin Holladay
by Charles Herrick

Yep. I'm in Texas (now).


116.
Dec 9, 2015 10:22 AM ET

The payoff is going to depend
by Sherwood Botsford

The payoff is going to depend on the climate. Some people mention R-60 ceiling. Makes sense if you have a 10,000 degree day heating climate. May make sense in an extreeme cooling climate. In Central Washington with mild winters and hot, but dry summers? Maybe not.

Once you get much above 2x6 standard construction, infiltration is a bigger source of heat loss than conduction through the envelope. The PGH needs an affordable heat recovery vent system.

Windows: Lawrence Livermore's house model calcuator shows a south facing R2 window to outperform an R3 window in a 10,000 degree F day climate. The R3 window loses more insolation from the less than perfect transparency of glass. The down side of this is the temperature fluctuation in the sun space. Mass helps here.

The cost of R5 windows is unreal. And so far in my reading, the argon fills tend to be R5 only for a few years. In a really cold climate radiation through the window is significant. With 100 F across the window there is roughly a 75 w/m2 outflow. (Based on black body cavity approximations.) An inexpensive automatic blind system would have merit here. Something powered by a solar cell and a floppy drive stepper motor. In the morning when light hits it, the blinds raise, when evening shadows fall, they lower. Tune the sensitivity so you can wait for full sun or just bright sky. Time over-ride. E.g. You get an hour of open for each time you punch the up button, then it reverts to automatic mode. Mode switch to try to keep house warm or cool. Schedule. The controller should be doable for about the same price as a digital watch in quantity.

Basements: Here our ground temperature is 10 C (50F) Ignoring the difference between conduction and convection losses, R40 in the attic space with 100F across the insulation (-30 outside temp, 70 inside) would be equivalent to R8 under the slab. My problem with my present 30 year old house is that the basement gets too warm. I want it to be 50 F so that I have a cold room to sleep, store books, plants, squash.... I'm considering at this time insulating the ceiling joists in the basement.


117.
Jan 13, 2017 4:53 PM ET

Pretty Good House specs for Hot/Humid climates
by Robert Hallenbeck

Following up on comments 7, 65 & 112: Has anyone published suggested specifications for a Pretty Good House in a Hot/Humid climate (zones 2, 3)? I'm in the process of building a garage apartment & a deep energy retrofit of a different house, however trying to decide how far to go (i.e. add rigid exterior Insulation to new 2x6 walls?). In an era of $0.05/kWh power (actual rate on last months bill), justifying significant upfront investment can be tough, even for those who care deeply about environmental performance. Would also welcome references to any academic analyses that attempt to prioritize decision-making or quantify environmental performance.

Thanks,
Rob


118.
Jan 13, 2017 5:37 PM ET

PGH hot humid
by Charlie Sullivan

Robert,

My subjective opinion is that the priority in a hot/humid climate shifts towards controlling solar gain (shading works well and can be inexpensive) and controlling infiltration. ERV for ventilation and HVAC system issues such as avoiding leaky ducts in unconditioned attics also seem pretty important. I don't want to tell you not to add insulation to your walls, but I think that making sure you have done really well on the other stuff is a higher priority.


119.
Jan 13, 2017 6:09 PM ET

Allison Bailes did a nice job
by Michael Maines

Allison Bailes did a nice job of describing a hot/humid PGH in a 2-part series:

http://www.greenbuildingadvisor.com/blogs/dept/building-science/pretty-g...
http://www.greenbuildingadvisor.com/blogs/dept/building-science/pretty-g...


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