Efficient is as efficient does
Quality building is all about efficiency these days (or it should be) and most people immediately think “well of course – it's good for things to be efficient”. But what are we talking about when we talk about efficiency? Materials, building practices, ongoing use? Yes.
It is important to start out by recognizing that efficiency has always been a consideration to one degree or another in building. There is a humorous meme circulating that shows three images of pyramids from three different parts of the world – Egypt, Indonesia, and Mexico with the question – “What does this mean?” The point of the question is to suggest some mystical, supernatural, or extraterrestrial assistance to make this happen. One person replied – “It means this is the most efficient way to pile up rocks and not have them fall down for a long time.”
Efficiency is about saving energy and building smart – both of which can contribute positively to the environment. Thousands of years ago building huge monuments meant pyramids no matter where they were built because without mortar and structural reinforcement (like rebar and metal beams), a straight up tower would just fall.
When talking about efficient building methods one thing you are going to hear a lot and need to understand is R-value. What is R-value and how does it relate to efficiency?
R-value is a measure of how well a material resists heat. The higher the R-value the more resistant to heat, which means the greater the insulation value. Look at it this way – if it is 35 degrees outside a high R-value in your home insulation means it takes a long time for that heat to penetrate your home. In the winter it works in reverse – the higher the R-value the longer it takes for heat to leave your home.
This is why understanding the R-value of your building and the materials used is important. The higher the R-value the less heating and air conditioning required, which translates to savings on your part. According to Manitoba Hydro, 13 percent of the province’s energy consumption goes to heating homes.
In a Manitoba climate it is required by code that you have an R-value of 50 in your attic insulation. When Hive Development Group built the Lexington Condos on 9th, we insulated the roof with 20 inches of cellulite to an R-value of 70. Further to this when we build our standard wall, it is R-22. Triple pane windows are our standard as well.
Of course, a well-insulated home is only part of the battle. For efficiency’s sake you also need to mitigate/eliminate thermal bridging. Thermal bridging is the term for when a building material acts as a conduit through your insulation, allowing heat/cold to move along it, reducing the efficiency of your home. Wall studs (like a 2x4 length of wood that provides structural support) are an example of a thermal bridge between insulation. In a typical home, studs can make up 25 percent of your wall.
According to ProgressiveFoam “Energy loss through the sidewalls of a home accounts for nearly 35% of the total energy loss, more than windows (10%), doors (15%), the foundation (15%), and even the roof (25%).”
Advanced framing (also known as OVE - optimum value engineering) places wood studs at 24” on-centre instead of the normal 16”, which can lead to lower thermal bridging and uses less materials in the process. Francis Family Homes, our housing division, currently uses this method to help achieve Hydro Power Smart credits in their custom homes.
There are more materials and methods that can be used to mitigate energy loss and break the thermal bridge. You can apply a spray foam insulation along surfaces with thermal bridges. You can use insulated siding along the outside of the house.
Francis Family Homes and Hive Development Group use several methods depending upon the project and type of construction. For basement walls we often use ICF (Insulated Concrete Form). ICF is a hollow block made up of rigid thermal insulation walls that lock together like lego. Once the wall is built concrete can be poured down the middle allowing for a well-insulated concrete wall. Concrete on its own is not a good insulator. A one-foot thick concrete wall has an R-value of 1.28 while a typical ICF wall will have an R-value of R-28.
If you want to take insulation and R-value in your walls to the next level, Francis Family Homes has used a product called ICE panels from Manitoba company Greenstone. ICE, or Insulated Composite Envelope, is a building system that lets you construct structurally sound walls without the use of concrete or wood, eliminating issues with poor R-value and thermal bridging. ICE is made from expanded polystyrene and galvanized steel struts that do not bridge through the product. The result is a wall with an R-value of R-50 for under 12” of wall thickness. Greenstone estimates a 2,000 sq. foot home built with ICE would spend approximately $67/month on heating versus more than $151/month for a traditional wood framed home.
It is also important to note how things like orientation of the home or building can affect energy efficiency. Ensuring the structure has south facing windows allows for solar gain in the winter, saving on heating costs. Roof overhangs can be designed to block the sun in the summer, allowing less heat into the building. Effective window coverings in the summer also ensure air conditioning costs remain low.
Understanding R-value and thermal bridging are two significant steps toward building a zero emissions home or business. Stay-tuned for our next blog post when we talk about the goal of zero-emissions construction.
If you want more information on building efficiently email us at firstname.lastname@example.org or call 204-823-0598.