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In a recent post I claimed you only need to know about twelve concepts in a given field to look like an expert compared to someone who only knows two or three concepts. A reader asked me to list the dozen concepts for building an energy-efficient house. I will take that challenge and list them here, compiled from my own research. Actually, I will list more than twelve for extra credit.

One caveat is that this list applies to a Northern California climate where air conditioning is more important than heating. Here's the list. My blog interface doesn't allow them to be numbered:


  1. The Roof and windows are far more important to insulating the house than the walls. Your walls won't be the weakest link, and you don't need any exotic insulation type.

  1. A radiant barrier for the roof is one of the best ways to keep heat from entering the house.

  1. Windows are rated for their thermal efficiency. It makes a big difference if you get the most efficient ones.

  1. Clay tiles, with lighter colors, are the best choice to reduce heat.

  1. Common wisdom says an attic fan is great for removing heat. A better approach is to design the home so there is a natural chimney effect, taking advantage of the fact that hot air rises. All you need is a ground floor window you can open on the cool side of the house that has metal bars (for security) and a screen (for bugs). Then open an upstairs window and the air will circulate up and out without a fan.

  1. Orient the house so there are relatively few windows on the hot western exposure. Shade the windows on the hot side of the house with trees that lose leaves in the winter, or shade the windows with a porch.

  1. Add plenty of thermal mass inside the home to act as a natural heat regulator. That means concrete, stone, and tile.

  1. Add solar panels, tied into the electrical grid. With rebates, and the cost wrapped into the mortgage, they are cash positive from day one. If you retrofit later, and they are not part of the mortgage, the payback takes maybe 20 years.

  1. Water heating is a big component of your energy bill, but no expert can tell you the best solution. Common wisdom says tankless water heaters are best. But you might need a bunch of them, and they require maintenance. Some experts say continuous circulating water heaters are now nearly as efficient as tankless, without the maintenance hassle. New gas condensing types are just hitting the market, with even greater efficiency, but they don't have a track record.

  1. If you talk to ten experts in this field, you will get ten different opinions for your home. Although rules of thumb are mostly consistent, every house is different, and without detailed engineering, which is impractical, there is still a lot of guessing.

  1. Gas is cheaper than electricity.

  1. Use Energy Star certified appliances when possible.

  1. Keep your ductwork sealed (you can test for that), and insulated, and within the insulated envelope of the house as opposed to in a hot attic or cold basement.

  1. Keep your AC compressor and condenser on the shady side of the house. It makes a big difference.

  1. Take steps to reduce humidity inside the house to make it more comfortable during hot weather. For example, don't have houseplants, and use your bathroom exhaust fan when showering.

  1. In this climate, assuming you insulated properly and managed the sun exposure, your best choice for a heating unit is a standard forced air type, engineered so it isn't too big for the job. The more exotic heating solutions such as geothermal only make sense in more extreme climates.

  1. Small houses are more energy efficient than big houses. Duh.

  1. Use LED or compact fluorescent lighting when practical.

Your first impression of this list is that it's mostly obvious stuff and you assume builders are doing it already. But I am writing this from my office inside a newish townhouse (six years old) that violated most of the concepts on the list. All I have going for me is Energy Star appliances, compact fluorescent lights,  and no house plants.

If you remember these concepts, you will know more about home energy efficiency than 99.99% of the general public. You may commence acting smug.

 
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0 Rank Up Rank Down
Apr 2, 2009
I went and done did it on my blog: Now anybody who can read Norwegian can become an expert on personality testing.

http://www.grendel.no/blog/2009/03/28/bli-ekspert-pa-personlighetstesting/

I happen to be one, so I went ahead and tested if I actually know 12 distinct things about it. Turns out I had to leave a whole lot out, so yes, the rule holds for personality testing.

Except that it won't work with HR Departments, since they, as a rule, can’t tell the difference between 12 true facts and 12 made-up facts.

Holler if you want it in English.
 
 
+1 Rank Up Rank Down
Mar 28, 2009
If you want to get unbiased comments you should check out the US Green Building Council LEED website. Also before hiring an Architect, (or God forbid an Energy Engineer like me), you should make sure they are LEED Accredited Professional (LEED AP). Tell your architect your want your new home to be eligible for Platinum LEED certification and you will be guaranteed maximum efficiency and minimum environmental impact too.

When building your house ORIENTATIION is imporpant. Set the roof up for a South facing orientation and make the angle of the roof roughy equal to your latitude. Talk to a solar panel installer and he'll tell you why. Don't worry about the color of your roof, cover the entire thing with panels.

Email me if you have any questions,

Craig
 
 
0 Rank Up Rank Down
Mar 25, 2009
@ Scott

Interesting you say rainwater tanks wouldn't be approved, but if they're done properly there's little maintenance.

I don't know what the imperial equivilent is, but 1mm of rain on one square metre yeilds 1 litre of water. If your roof surface area is 100 square metres and you get 100mm of rain a year, that's 10,000 litres of water you catch each year.

In some states in Australia, they give subsidies if you get a water tank installed and also have it plumbed to the toilet and laundry. I use mine to keep my garden and lawn alive through summer. This year we had a number of days around 44 degress c (110f.)
 
 
Mar 24, 2009
Is it possible to heat your water tank with the waste heat from your air conditioning system when it is running? It seems like this is an entirely free source of heat.

I have heard of a system that ran water pipes behind photovoltaic cells to make hot water and power from the same solar energy at the same time For example: http://www.earthtoys.com/news.php?section=view&id=6066

Of course, outside the summer months, you'd probably need an additional source of heat for hot water than these two.
 
 
0 Rank Up Rank Down
Mar 24, 2009
Scott Adams wrote: "Add plenty of thermal mass inside the home to act as a natural heat regulator. That means concrete, stone, and tile."

You'll regret that, especially if the concrete, stone, and tile are part of the floor. When that thermal mass gets cold in the winter, it sucks heat out of you like the dementors in Harry Potter, and it's difficult to heat since heat rises. We add some area carpets in the winter, but it's a hassle and it doesn't help enough, and as a result, we end up turning the thermostat up higher to compensate.
 
 
0 Rank Up Rank Down
Mar 24, 2009
Scott, can you share what solar panels you are using? Looking into adding them to my roof, but I vaguely recall being told Texas is a state where you can't sell the power back to the grid (unwinding your meter so to speak).

[Haven't selected them yet. House is still being framed. -- Scott]
 
 
0 Rank Up Rank Down
Mar 24, 2009
I think maybe you could get the ordered list numbers to go up if you didn't write each one on every other line. So rather than this:

1.

1.

1.

You could do this:

1.
1.
1.

Just a guess, of course.
 
 
0 Rank Up Rank Down
Mar 24, 2009
Solar hot water heating is the way to go I have had it installed on my house for going on 4 years now and it cut our power bill by over 1/3 pay back around the 7 - 10 year mark depending on the type of system you have installed
I had to have the slightly more expensive type fitted due to the shape of my roof. this combined with instant gas hot water would be perfect so if you have 3 days of no sun the gas kicks in when the water temp drops below a set point.

[Yes, should have been on the list. Those systems are embedded in driveways now too. -- Scott]
 
 
0 Rank Up Rank Down
Mar 23, 2009
Where's the bit about installing an underground rain water tank when building? Catch the rain water, use it for the garden (to water those trees on the sunny side of the house) and to maintain a real lawn.

[Those systems are potential maintenance headaches wouldn't be approved in my area anyway. Plus it only rains three months of the year. -- Scott]
 
 
0 Rank Up Rank Down
Mar 23, 2009
Speaking of energy efficiently, check this article out: http://www.inhabitat.com/2009/03/23/the-ecodrain-cuts-water-heater-use-by-40/

[Looks promising. -- Scott]
 
 
Mar 23, 2009
Nuclear (and i believe hydro-electric dams) are far more efficient than solar. Also, the toxic materials used in solar panels are worse for the environment than the small amount of waste produced by nuclear plants. While you might make a profit with solar, getting nuclear power from the grid is more environmentally friendly.
 
 
0 Rank Up Rank Down
Mar 23, 2009
Very few people understand how valuable it is to put your HVAC ducts in conditioned space.
Even the ones who do find it difficult to give up indoor space for mere ductwork.
 
 
Mar 23, 2009
BTW, did you do anything about water? Like using gray water for toilet flushing?
 
 
+1 Rank Up Rank Down
Mar 23, 2009
Hey, great list. Took me 2-3 semesters of architecture school to learn all that.

Most houses violate these rules because they are build for selling. After you buy it, it's your problem. Like how people WANT Hummer or Corvette, while they SHOULD get Prius. When people view the house, they tend to want lots of windows with lots of sunlight. Only when they move in that they realize it is inferno.
 
 
Mar 23, 2009
Great post, Scott. Good info, all.

Some other things: it takes more energy to bring a house up from a cold-soaked condition, or bring it down from very hot, than it does to keep it about ten to fifteen degrees differential all day. When we have a hot spell here (I live about 20 !$%*! from you in Contra Costa County), I have found that, if you turn off the air conditioning while you're out of the house, and the house heats up above 85 degrees, your air conditioner will be on continuously and probably won't be able to cool the walls enough to allow the house to cool down.

So in general, leave your air conditioner on when you're out of the house during the day, set at about 78. You'll use less energy overall and you'll be able to cool your house when you get home in the evening. I realize you work from a home office, so it may not be of much help to you, but in general it's a good idea.

Another simple thing to do with forced-air heating and cooling is to close off the vents in rooms that you rarely use, and keep those doors closed. Open the vents wider in upstairs rooms when cooling and in downstairs rooms when heating, for reasons that should be obvious.

And let's hope we get some more rain. This drought thing sucks.
 
 
Mar 23, 2009
Reminds me of all of the concepts that went into "Dilbert's Ultimate House" (aka DUH). Definitely going green. Your advice provided on building DUH definitely qualifies you as an expert in my opinion. I've thrown out several of your ideas to local contractors on "going green". Thanks, to you, of course.
 
 
Mar 23, 2009
So, would it be safe to completely reverse most of these if I wanted to adapt them for a more northeastern climate, like Maine? Perhaps you wouldn't mind taking some time to rewrite these rules for each of your loyal follower's individual homes? Just kidding. Thanks for this though, it gives someone a starting off point to ask questions. If the contractor thinks you know what you're talking about, he's probably less likely to snow you. I'm going to the Ideal Home Show this weekend, so I'm hoping to learn something new.
 
 
Mar 23, 2009
How long does it take to learn the twelve rules of a subject given the ambient level of obfuscation?
I'd love to see a book or pamphlet with Scott Adams generated and complied sets of twelve rules on as many topics as possible.
 
 
Mar 23, 2009
One more thing ...

I know that various hot water heating systems all have their location-specific cost-benefit analyses, but I've used gas- or propane-fired (not electric!) tankless systems for years, both in the US and overseas, with no problems whatsoever. One caveat: Use tradition hot and cold taps, rather than single-lever mixing valves; otherwise, the tank fires up every time you turn on the water unless you remember to swing the lever all the way to the cold side.
 
 
Mar 23, 2009
As a retired builder who worries about life-cycle costs, I offer these suggestions from my own list, in no particular order of importance:

Without a reason to do otherwise, bedrooms go on the east to catch the morning light, rarely inhabited or ‘hot’ spaces (closets, storage, utility/laundry, kitchen, etc.) go on the north to buffer the cold and wind, and the garage goes on the west to block the summer sun.

Splurge on a screened porch, at least 12’ x 16’. Removable acrylic or glass panels make it a 3- or 4-season room that can easily be enclosed in cooler weather. Trust me on this -- you’ll use it all the time. For lack of a better place, separate the garage from the house by 12’ and bridge the gap with the porch.

Insulation, caulk, and expandable spray foam are cheaper than fuel. Seal all horizontal and vertical penetrations in the boundary of the conditioned space, as well as gaps between adjacent framing members. If you want a quiet house, do the same with interior partitions, and never put opposing outlets in the same stud bay.

Stack the plumbing or plan it back-to-back to minimize plumbing runs. Using a central manifold with a home-run water distribution layout eliminates all those isolation valves at individual fixtures that never work when you need them. PEX has an established reliability record, costs about the same as copper, and is a snap to install.

If you extend the rafter tails down to near the top of the door and window openings and cut them parallel to the ground, you have ‘all soffit, no fascia’ with a wide overhang that shades all the windows and pretty much ends the need for gutters.

Make seldom-used rooms, if you include them at all, do double- or triple-duty. There’s no reason an intelligently planned dining area can’t also function as a library/office, or a guest room as an office, media room, or home gym. If you make almost any room 1-2’ deeper on one wall and cover it in shelving/cabinetry, you won’t be sorry.

ICFs (insulated concrete forms) can easily get you an R-30 wall (that's also bullet-proof!) for about a 10% premium over conventional framing. If you're worried about the energy component of all that concrete, add fly-ash. You'll also end up with a very quiet home (no outside background noise), so choose your fridge, air handler, and other noise-makers with care, or they'll keep you up at night.

If you haven't read Sarah Susanka's series on the "no so big house," do so. Better yet, hire her.

Walk through the plan in your mind for at least a year; changes are cheap on paper, but expensive in the field. “Where does the Christmas tree go?” is just one of the 30,000 things you’ll need to decide. All houses (and spouses) have 10 flaws –- pick 10 you can live with.

Good luck with your project!
 
 
 
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