For the Wain Rd Project this is our story…
When Damon Gray, from NZ Builders ltd. decided to build his own home he decided to take a different approach to the traditional Canadian build.
Coming from a home country with harsher climate considerations, his view on building was already different from most. The UV index is much higher in New Zealand and with 2000 hours of sunlight on average, and 500 mm of Coastal rain (torrential, horizontal rains), New Zealand has much more stringent building requirements. With electricity costing 30 cents a kWh (about three times our costs here in Canada), Damon is also used to conserving energy. Damon also has two young children, a fact which figured significantly into his plans. Key points that had to be considered:
- Low Maintenance Building method
- Healthy Environment
- Capital Costs analyst over Maintenance Costs.
- Passive Solar design for natural light and Energy Savings.
- The home had to be a piece of art.
The home was constructed using a concrete sandwich panel building method. The team at NZ Builders improvised by taking tilt up construction from the commercial industry and using it in the residential sector.
Concrete sandwich panel homes offer a large range of benefits for homeowners and the environment. These homes are very low maintenance. Rot, mould, and fire issues are removed, and building with the correct design and insulation envelope can reduce total heating and cooling loads from 25%-80%, depending on how seriously you design your home.
Purchasing the property.
We looked at the solar array and the way the property faced. South facing gains you all day sun. But shading of trees and building were a problem. Utilities to the street are something to consider. Gas and Electric or just electric. How green did we want to be? Which is greener gas or electric. That’s a good debate.
We decided we were green as we do recycle our rubbish and are looking to save energy in the build.
We found property with 98% solar array which means there is sun from morning to evening. So what was that particular property worth to us with 1200-1300 average sun hours? This would generate about $1,100/year of heating to the home. At todays mortgage rates this is roughly about $20,000. So why purchase a property that has the same qualities as one that is $100,000 les and has a 25% less solar array.
We decided to buy the less expensive lot with the knowledge that if we were that upset about the loss of solar gain we can always spend a third of the $100,000 on solar photovoltaic panels and get more back than the loss of 25% solar array.
There was no gas service to any of the properties. Gas is 2 times less to purchase than electricity when buying heat. Again if you have gas service to your property this is worth $20,000 as a capital investment at today mortage rates.
Design was important to us in receiving sunlight to our home for health and for passive heat. There are trade off that ding your annual costs but if you know these up front then these help with your decisions.
We decided to have a large overhang to shade us from the summer sun so there was no need for Air Conditioning. The calculation on this overhang to optimize winter sun is something the myan’s used long ago.
The over hangs and window height of your home will control the heating and cooling through the shoulder months as well. The fluctuation of heat becomes minimal allowing you not to rely on a mechanical system to control your comfort.
Having a single story house that was wheel chair accessible was a detriment to the heat load. Double story house that is a square is close to ideal.
Through out the design we concentrated on the homes ambience more than the energy efficiency as you can get caught up in the energy consumption. We also knew the cost to chase the ultimate energy consumption has a logging effect and the more you chase it the more is costs. So there is a scale of economy where you have to draw the line.
The build process, included insulated footings, high performance windows and details that eliminated thermal bridging. Your ultimate goal is to get your effective R value as high as possible. Heat goes to the least path of resistance. Example if the ground is 10 degrees and the house is 20 degrees and you have no insulation between these points then your heat will go downwards. In an average home this accounts for 20% of energy loss. This became very important as it is an area that is very hard to renovate once built.
When it came to the heating system we were running costs analysis, lifespan of product, maintenance of the product. How were we going to heat?. Air to water radiant in floor heat? Geothermal to Radiant floor heat?, Electric Boiler Radiant in floor heat?, Forced air?, Electric heat matt? Mini split heat pump? Wood burning boiler? Wood Burning boiler?
We ended up with an electric boiler with radiant floor heat. What confirmed our decision on the fact as if we were to buy a high efficiency heat system we still had to pay to power this equipment and it was a product that a professional had to fix. For the same cost we could buy all the Solar PV we wanted and have little to none maintenance. Just another reason how solar PV crept into our lives. Some people buy Geothermal we brought Solar PV. Solar PV had to many benefits not to say no. Solar PV he greenest energy if you are grid tied. We are not tied to a commodity that can change it’s rates over night. Solar PV supplies your house with its needs, travels to the meter and gives you a credit that you can then use in the winter. When it travels out your driveway it supplies the next place of demand. Your neighbor. Most people don’t know when power is produced at its source when leaves to travel to its destination it has resistance or loss of power. In other words to supply an average home on Vancouver Island with power it has to produce more at the source. So having solar PV you cannot get much closer to the source. So we feel we are doing our part for the environment.
If you took solar PV as a straight up investment you may break even with a RSP.. In ten years the return on investment for Solar PV will be different story.
Because the concrete provides a very airtight envelope it was important to have a mechanical ventilation system. We used a 90% efficient HRV system that originated in Europe and is now being sold in north america.
In fact the roof membrane, gutters, windows and building method all originated from Europe. As a country we should be looking at what the Europeans are doing in the building industry. We seam to like buying there cars.
When the finishing’s came into play we wanted durable products with west coast modern home.
The property had trees that provided us with all the interior and exterior wood finishes.
As a company we do look at ourselves as the Tesla of home building. (personal opinion) We are always working on perfecting the residential building techniques and performance. We will be pushing cliental to spend there money on equity rather than liability. With new products coming out all the time the building industry is exciting to be in.
People always want to know the cost of the home. We are 10% more than conventional wood frame. The home on wain rd was $240 a square foot. We have 3000 sqft of home and 750 sqft of garage. Wain Rd contains 4 bed 4 bath. Concrete panel homes can be built from $160 a sqft based on 3000sqft.