Author Topic: how to build an energy efficient home  (Read 2873 times)

going2ER

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how to build an energy efficient home
« on: June 28, 2016, 11:11:56 AM »
In the next several years we are looking at building our "retirement" home. It will be a raised 1 story with a finished basement, much smaller than our current home. We currently have roughly a 2000sq ft home with a blended family of 5 children, 2 are still at home, likely with one leaving in 1-2 years, the other in 10 years. The property we will be building on is mainly level. Our winters go to about -20C at the coldest, but maybe -10C for an average and summers up to 30C, but 20C as an average.

We are looking at triple pane windows and hoping they become more common in the next couple of years and that the price comes down. We are able to purchase them locally.

We are investigating a geo-thermal heat pump, common in Denmark with a similar climate. There just isn't anyone in the local area that installs them. We currently have oil heat which is incredibly expensive, but that is the most common type of heating fuel in this area and we want to stay away from it. Gas is not available nor do I see it being available in the coming years.

Any ideas for insulation? roofing? or anything else that would easily make a home more energy efficient?

homestead neohio

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Re: how to build an energy efficient home
« Reply #1 on: June 28, 2016, 11:44:59 AM »
Where are you?  Northern climate?  Woodland or open?  What are your goals?  Do you just want cheap utility bills, or do you want to be leading edge and have almost no utility bills?  Do you want a house built with natural materials, or modern conventional construction?  Passive solar design is good (orient windows south facing with overhanging roof to provide shade in summer, high thermal mass like a concrete or stone floor to store and radiate heat from winter sun).  Earth berm the N side of the house, transitioning to a green roof.  If I wasn't going to stay where I am forever, I'd buy some land and build a WOFATI.  Supposedly no need for HVAC, but I'd like a small woodstove in there.

https://paulwheaton12.wordpress.com/2014/11/20/wofati/.

I'd put way more windows on the S wall, than this example, though.

If that is too "rustic", there are some cool things going on with super-insulated buildings, but they are pricey to build and cheap to run.  Look up zero net energy homes. 

We have local installers for geothermal heat pumps.  They are pricey.  We retrofitted our old home with a ducted mini-split air source heat pump instead.  We could install that with a solar PV system to power it for the price of just the geothermal, which would not even work with our geology (shallow bedrock).  When we installed this, we sold the used oil furnace and traded the heating oil for some straw.

MrSal

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Re: how to build an energy efficient home
« Reply #2 on: June 28, 2016, 12:22:32 PM »
Forget the triple pane windows... They don't add that much more in insulation. Instead go for hinged windows instead of the hung windows that prevail in the US unlike in Europe ...

Like these ...

They are much more air tight than normal sliding windows.... triple pane are much more expensive for so little jump in r value they give

laughing_paddler

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Re: how to build an energy efficient home
« Reply #3 on: June 28, 2016, 01:06:27 PM »
I just investigated options for doing some energy retrofits while undergoing a partial re-side of my 100-yr old house and found greenbuildingadvisor.com to be very helpful . Be prepared to do lots of reading.

going2ER

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Re: how to build an energy efficient home
« Reply #4 on: June 29, 2016, 07:11:37 AM »
Where are you?  Eastern Canada
Northern climate? yes
Woodland or open?  open, in a town
Do you just want cheap utility bills, or do you want to be leading edge and have almost no utility bills? we would love low or no bills. We are more concerned with heating then cooling.
Do you want a house built with natural materials, or modern conventional construction? we are open to a mix

While there are some large trees on the property I don't think a Woofati would work for us. Our current home would actually be considered partly an earth berm. It was built over 100 years ago so I don't know how much they considered when building into a hill. Our front door is on the first floor, our back door on the second. Our kitchen is in the space that is mostly underground and I would highly recommend this type of building. In the winter it is warm and in the summer I can cook a turkey dinner on the hottest of days and the house doesn't over heat.

My husband does prefer outswing windows and doors as when the wind blows in the winter it does tighten the air barrier rather than increase it, so we were planning on skipping the hung windows. I'm in Canada and find that there is a good mixture of hung and hinged windows. I didn't realize that triple pane would not increase efficency that much.

Thanks for the webside Laughing_paddler I will spend some time going through it.

We will likely be meeting with an architect over the fall/winter so I want to know exactly what we will be using in case any adaptations will need to be made to the plans. Please keep the ideas coming.

Telecaster

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Re: how to build an energy efficient home
« Reply #5 on: June 29, 2016, 07:43:52 AM »
This is a very broad topic, but in general yes windows are the last place to spend money (despite what window salesmen tell you).  Basically, you want to insulate the shit out of the walls and roof.   There is a technique called advanced framing that uses less wood and allows more insulation: 

http://apps1.eere.energy.gov/buildings/publications/pdfs/building_america/26449.pdf

The problem is that a lot of builders don't know about it, so they don't know how to do it.  But that's how you need to do the framing. 

The way most houses lose energy is by simple air leakage.  So you want to make the house really, really tight.  But once you get that tight, you don't have enough fresh air for the occupants, so you need something like this: 

https://en.wikipedia.org/wiki/Energy_recovery_ventilation

The issue with geothermal heating (I hate that term, a better description is ground loop heat pump) is that it doesn't work if the ground get really cold, which it sounds like it might in eastern Canada.   That might be why nobody does it in your area. 

One final word on windows, in the US, windows are rated by the U-factor, which is to say insulation.  But I understand that in Canada they also rate windows by the solar gain.  That's something I don't know much about, but you will also want to capture solar energy, as well as preventing energy from leaving the house.  Something to consider when buying windows.


historienne

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Re: how to build an energy efficient home
« Reply #6 on: June 29, 2016, 09:28:25 AM »
We looked at Go Logic and Unity when we were considering building in the Northeast US.  Both are prefab builders that do near-passive construction.  I don't know if they do work in Canada or not, but they are designing for a reasonably similar climate.

SimplyMarvie

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Re: how to build an energy efficient home
« Reply #7 on: June 29, 2016, 09:30:56 AM »
Is something like straw bale construction an option? High R value in the walls, and very easy/cheap to put together. It's our plan for the cabin we'd like to build in the next 3-5 years, but we'd be in the mid-atlantic mountains.

Prairie Stash

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Re: how to build an energy efficient home
« Reply #8 on: June 29, 2016, 02:42:43 PM »
Rob Dumont was a researcher who practiced his work and built a energy efficient house in 1992. He published all his costs and utilities for many years, you can find all of them online. He estimated his additional build costs to be 7%, which was paid for (in savings) in 10 years. I linked 2 to get started:

http://www.greenbuildingadvisor.com/blogs/dept/guest-blogs/robert-dumont-s-superinsulated-house-saskatoon
http://www.cchrc.org/docs/sns/Dumont-Abstract.pdf

Also look up Factor 9 house, a more recent design (things have improved in 25 years). The CMHC has lots of useful information

You can skip geothermal, heat pumps etc. and get more insulation; it worked in a climate that gets -40 C.  Its a mind blowing revelation to just skip a furnace, its possible to build houses without them in Canada. Typically people are more comfortable as well, temperatures tend to stay more consistent.

nereo

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Re: how to build an energy efficient home
« Reply #9 on: June 29, 2016, 04:00:02 PM »
posting to follow, as we've been pondering doing something similar in 3-5 years.

I'll just add that, in eastern Canada you might want to give serious consideration to designing your house to have as high solar heat gain as possible in the winter.  Large insulated south-facing windows with a floor that can absorb and store a large degree of thermal mass (concrete is often the go-to, though it adds a lot to the initial carbon footprint of the house).

In the summer you can keep the home cool by having permenant or semi-permanent awnings to shade the interior from direct sunlight, though this is less of a problem for you than staying warm in winter.

There's a really facinating demonstration eco-house at the Jardins de Métis in Quebec (Mont Joli). If you are ever in the region it's worth checking out (plus the gardens are beautiful too).
http://www.refordgardens.com/english/#3

BDWW

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Re: how to build an energy efficient home
« Reply #10 on: June 29, 2016, 04:36:59 PM »
One thing I'll mention that should be done in colder climates, an externally insulated foundation. Especially if you have large variances in vapor pressure (ground water, ie snowmelt in the spring).  For some reason people (and the vast majority of contractors) try to insulate inside the foundation. This is never a good idea. Even if you install proper vapor bearers on both sides of your interior (foundation) walls, you still have a rim joist that rests on the foundation allowing vapor and heat transfer.

Your foundation should be thought of as part of the interior of the home. The slab should be poured over rigid foam. The walls should be set on a footing separated by a vapor barrier. Then sealed from the outside, and insulated from the outside, stretching up to cover the rim joist. This prevents almost all of the issues a finished (insulated) basement is usually presented with.

homestead neohio

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Re: how to build an energy efficient home
« Reply #11 on: June 30, 2016, 07:09:22 AM »
One thing I'll mention that should be done in colder climates, an externally insulated foundation. Especially if you have large variances in vapor pressure (ground water, ie snowmelt in the spring).  For some reason people (and the vast majority of contractors) try to insulate inside the foundation. This is never a good idea. Even if you install proper vapor bearers on both sides of your interior (foundation) walls, you still have a rim joist that rests on the foundation allowing vapor and heat transfer.

Your foundation should be thought of as part of the interior of the home. The slab should be poured over rigid foam. The walls should be set on a footing separated by a vapor barrier. Then sealed from the outside, and insulated from the outside, stretching up to cover the rim joist. This prevents almost all of the issues a finished (insulated) basement is usually presented with.

+1.  I can't remember where I read this, but an un-insulated foundation on an insulated house is like standing in a hole outside in the winter with a hat, gloves, parka, and no pants.  Also +1 to air leakage being more important than insulation.  We air-sealed and insulated our very old farmhouse and burn less than 1/2 the wood we did in prior years.

csprof

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Re: how to build an energy efficient home
« Reply #12 on: June 30, 2016, 08:41:44 AM »
Joseph Lstiburek's "Builders Guide for Cold Climates" is one of the best treatments of the topic:

https://buildingscience.com/bookstore/books/builders-guide-cold-climates

It's $45 - your local library may have a copy.  If it doesn't, it's worth every penny, as is taking the time to read through some of the articles they've published in the BSI series.  They've got a lot of case studies in there that help illustrate the points.

It's not a casual evening read.  But my goodness, it's comprehensive.