Does your client have champagne tastes for comfort but a beer budget for construction of their new home? We've got tips for top performance at an affordable price.
Building a house that complies with the strenuous Passive House standard requires a large investment that is off-putting to many margin-conscious home builders. Many homeowners are keen to lower their home’s carbon footprint and running costs, but often the significant upfront investment of this kind of design is a high hurdle only cleared by the most committed.
However, smart home builders are learning that they can copy high-end constructors to build homes that are incredibly comfortable and energy efficient but are marketable to a broader range of prospective home buyers due to better all-round comfort that includes thermal stability, abundant daylight, great noise suppression and fresh air at an affordable price point. These builders have learnt that they don’t need to blow the budget with commercial grade fixtures if they think critically about the home’s construction and look at the areas where thermal bridges and outside air can compromise the home’s heating and cooling performance, from the floor to the ceiling.
Here are some areas that builders and homeowners can keep an eye on during planning and construction of new homes:
Tape it tight
Study after study has shown that without airtightness, there's little or no insulation benefit. Identify all the usual leaky spots – windows, door frames, service outlets, foundation-framing seams and roof-framing seams, and get them taped or caulked.
There have been numerous studies conducted on air tightness, including large scale blower door testing of new homes by CSIRO. These studies have proved that while new houses may rate up to 6 stars, through gaps in construction and poor attention to detail, many are achieving 3 or 4 stars in actual thermal performance.
A recent CSR study found that a properly installed and well-sealed air barrier wall wraps play a critical role in improving energy efficiency by restricting uncontrolled air leakage.
Frame the savings
Consider items such as the framing. Standardising at 600mm centres for framing elements can be a more efficient (and therefore cost-saving) way to install more insulation and less timber without affecting structural performance, plus the electricians and plumbers have fewer pieces of timber to drill through when roughing in. Smarter techniques include avoiding mass collections of studs in corners and around smaller windows, however check the framing code first to ensure the structure is not compromised. Any approach to maximise insulation coverage will have obvious acoustic and thermal advantages, creating energy savings and a happier customer.
Retrofitting the walls between air-conditioned living spaces and unconditioned garages, laundries, bathrooms and/or underfloor areas can be a long-term homeowner headache but this is often where insulation is of great benefit. Are you insulating internal walls or raised floors? Should you add an air barrier? Insulation, ventilation and construction fabrics in these areas are an easy solution to the common problems of heat and noise transfer from areas such as underfloor, garages, and rooms such as laundry or kitchen.
"What's That Duct Doing in My Roof?"
Yes, what is it doing there? Avoid placing duct systems in unconditioned areas, especially roof spaces in cold or hot climates. There are ways around this in new construction, so consider making the adjustment. However if unavoidable, an insulated duct with minimum R1.5 can help reduce heat gain from roof spaces. If your home is highly efficient, smaller split system air conditioners can deliver huge savings in installation and running costs.
A quick spot check before lining
It's easy to do a walk-through of the framed home and hit any uninsulated areas your insulation installer may have missed with wrap, tape and insulation. Any uncovered spot is a big setback for home heat loss/gain. Also, check to see insulation cover is uniform throughout, BEFORE the internal linings are installed.
Smart windows = less HVAC
A superior weather-tight window with a Low U value can work wonders on reducing reliance on heating and cooling needs. Check it out: the extra cost for a better window could be smartly offset by a smaller, less expensive & more efficient HVAC unit.
Single Low E glazing like Viridian SmartGlass is more commonly becoming the standard for many window specifications and double glazing is also becoming more affordable.
Don’t forget double glazing is not just for cold climates; it stops heat flow through separation of surfaces and can reduce conductive heat flow INTO a building just as effectively so it’s great for hot climates too. Couple this with a low E surface such as with Viridian Lightbridge and you can “Uber” your window performance through thermally broken aluminium, UPVC or timber window frames to further reduce heat flow. Plain aluminium frames just don’t cut it anymore.
Talk it over with your tradies
Take the time to plan the build with your construction team, especially installers. Let them know that you're looking for their ideas and cooperation on weather-proofing, insulation and draft proofing. You might be surprised by the helpful feedback and extra installation diligence.
Remember, you don’t need to be building a Grand Designs house to create a better product for your home buyers or for the environment. Keep your eye on these affordable techniques to deliver a higher performance home to a happy consumer for a great price.
Building Knowledge will be focussing on health and comfort within buildings through 2016, articles will discuss air tightness, thermal stability, daylight, acoustics and effective ventilation.
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