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Rob Dumont

posted Oct 6, 2010, 2:12 PM by ASHRAE Saskatoon   [ updated Oct 6, 2010, 3:13 PM ]

How much insulation should you put into a new house?

There are several possible answers to that question.  A lot depends on your estimate of the future cost of energy and on your concern for the environment.

1. Here is the “Deep Green” option. Install enough insulation for net zero annual energy use.

Putting enough insulation in a house to result in a net zero house results in a lot of insulation in Canadian houses. R100 attics, for instances, have been used in some net zero houses in Edmonton and Saskatoon. Although this approach may seem radical, consider that in the United Kingdom that all new houses starting in 2016 will have to be net zero in energy consumption.

California has plans to make all new housing as of 2020 in the net zero annual energy category.

In our house in Saskatoon built in 1992, we put R80 insulation in the attic, R60 in the walls and R35 in the basement floor. We also used triple glazed windows with two low e coatings, argon gas, and low conductivity spacer bars. I have no regrets about making this investment.


Gary Proskiw, a seasoned mechanical engineer based in Winnipeg, recently completed a study with Anil Parekh of NRCan regarding the appropriate insulation levels to use in Net Zero Energy houses in Canada. They looked at the appropriate insulation levels to use for Net Zero Energy houses  in four climate areas in Canada—Vancouver, Winnipeg, Toronto and Yellowknife.


Location

Recommended Attic

Insulation Levels

 R value

(hr-ft2- F/BTU)

Yellowknife

 8500 Heating Degree Days C

80+

 Winnipeg

 5900 Heating Degree Days C

80

 Toronto  

3650 Heating Degree Days C

80

 Vancouver

 2925 Heating Degree Days C

60 to 80

             RSI 1 = R 5.678

As expected, somewhat higher insulation levels are recommended for colder locations. These insulation levels were chosen by using the following criterion:

Here is a quote from the Proskiw and Parekh paper:

“To improve a building’s energy performance, NZEH designers have two options at their 

disposal - various types of conservation measures and renewable energy systems. Conservation measures have several advantages: they are well understood, generally have an established track record of performance, are relatively economic and are (for the most part) durable. They can also be applied to virtually any house without major modifications to the design or impact on the occupant’s lifestyle. Adding moderate levels of conservation measures tends to initially produce significant savings at modest incremental cost. However, as the level of conservation increases, the rate of further savings declines and the costs increase. This trend continues until a point is reached at which the cost of saving energy using conservation is greater than the cost of producing new energy from renewables. At this point, the designer should direct further energy investments into renewable energy sources, even though their cost may be high since they are still less expensive than the competing conservation alternatives.”


This same approach was used by the designers of the Riverdale Net Zero Home in Edmonton, who ended up with similar insulation levels. The first time that I heard of this rigorous approach [adding insulation until the cost of energy saved was equal to the cost of the energy from renewable energy (photovoltaics)] was at a design charrette for the Riverdale Net Zero Home.

The one weakness with this approach is that while insulation, properly installed, has a nearly infinite life, photovoltaics, inverters, and solar thermal collectors do not. Thus, if anything, one would likely want to put some more insulation than those levels indicated in the above table.

The slightly more correct economic approach would be to choose the insulation levels that would result in the lowest net present value of the expenditures for insulation, renewable energy equipment, and heating equipment over the life of the house. Why this alternative? The key reason is that while insulation, properly installed, has no moving parts and nothing to wear out, will last for the life of the house, the renewable energy equipment and heating equipment must be replaced periodically.

Another side benefit of high insulation levels is that the cost of the heating system can usually be reduced. High insulation levels equal small heating systems. This approach has been championed by the Passive House (PassivHaus) movement in Europe, where over 10,000 homes have been built to this high standard. In Northern Europe, the standard heating system is often an expensive boiler. By eliminating the boiler, significant cost savings are possible.

For an excellent set of videos by a Net Zero Energy builder in Edmonton, Peter Amerongen, have a look at Youtube. http://www.youtube.com/watch?v=nxDUe4qnZtg

The videos show a lot of details that have been developed to keep the incremental costs for Net Zero houses at a minimum. To quote Peter Amerongen ,”Better housing will always cost more (initially, ed), but if we don’t focus on doing it efficiently and making the right decisions, it could be extraordinarily expensive.” Anyone involved with Net Zero housing in Canada must see these videos. Peter’s company has now completed at least three net zero energy houses in Edmonton.


2. Green Option. Select insulation levels to match the price of certified “green electricity” from your local utility. 

In Saskatchewan, for example, one can purchased certified green electricity for an incremental cost of 2.5 cents per kilowatt-hour. Certified green electricity in Saskatchewan comes from Wind generation. Conventional grid electricity is about 11 cents per kWh. 

3. Model National Energy Code Option 

Back in the mid-90s, a model national energy code for Canada was developed. At the present time, the code is being rewritten. Hopefully the new code will more seriously address climate change and the peak oil issue than the last edition. 

4. Local jurisdiction Minimum Code Values

A number of jurisdictions in Canada now mandate minimum insulation standards for new housing, and others just leave it up to the local market. 

When serious national objectives are at stake, Canada in the past has not “left it up to the local market.” We now have national regulations on automobile fuel efficiency and appliance energy use. I see no reason why buildings should be exempt. 

Canada will seriously miss its Kyoto target of a 6% reduction in energy use compared with 1990, in large part because of an absence of initiatives by the federal government. 

Nicholas Werth recently did a study for the UK government about climate change. He concluded that a carbon tax of $200 US per tonne of carbon dioxide emissions would be needed to seriously reduce greenhouse gas emissions. At present in Europe, carbon is trading at about $20 per tonne. A ten-fold increase in the charges will be needed to bring about needed reductions in fossil fuel use. 

Increased insulation levels are a simple, proven, and relatively inexpensive way to address carbon emissions and greenhouse gas emissions. Let’s get on with it. 

References: 
OPTIMIZATION OF NET ZERO ENERGY HOUSES
By Gary Proskiw, P. Eng., Proskiw Engineering Ltd. (pel@mts.net; 204 633-1107)
Anil Parekh, P. Eng., Natural Resources Canada BEST 2 - Energy Efficiency - Session EE3-3
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