Most energy-saving tips suggest you focus on what you can replace without breaking and going behind walls or under floors, such as LED lights, a programmable thermostat, and a better shower head. That’s all well and good. But it won’t give you the same bang as a structural remodel. When walls can come down, and floors can go up, the upside in energy savings, as well as lifestyle, aesthetics, and value, is so much greater than any single “do more with less” swap you can make (and people have been making them for more than a decade).
Heating and cooling represent about 40% of household energy use (Australian Government, YourHome). So, the “thermal envelope” is where the money is, the envelope being the living, breathing boundary between your nice, conditioned, inside space and the brutal, unkind world outside. Structured work is the only time you get access to it and can do anything about it for, probably, the next 40 years.
Make the Open-Wall Phase Count
The most important phase in any structural remodel is when the frame is out in the open. Once that drywall is put back, it’s too late. It’s time to fill the wall cavities with the highest R-value insulation your framing depth will allow, and to apply vapour barriers that would be physically impossible to install at a later date without tearing the walls open all over again.
And this is no tick-the-box exercise. The difference between okay insulation and best-in-class insulation at this point is relatively little in material costs; it’s the getting-access-to-the-cavity labour that costs money, and you’ve already invested in that.
If it’s an extension, think Structural Insulated Panels. They don’t perform better than good old stick framing if the stick framing is done with care and attention to insulation, but they can perform better if it’s just regular stick framing. And they’re quicker to build with, which can offset some of the material premium.
Align Your Floor Plan With Solar Orientation
Removing walls can be very costly and inconvenient. But it’s usually the only time you will have the opportunity to consider how the layout of your house interacts with the sun. For example, a living room that makes the most of the morning sun will be a warmer space in winter. And assuming your country has a pleasant summer’s day, you may wish you could open it up to catch some natural cross-ventilation when evening hits, and the house is overheated.
This is passive solar design. It isn’t an extra if the decision is being made anyway. It will be an extra if you base a poor floor plan (for solar or any other reason), then try to compensate for it through mechanical heating and cooling for the next 30 years. A rough solar analysis should be done at the same time as structural layout options are being explored. Some design-and-build teams do this as part of the planning stage, which they include in their service. Working with experienced professionals like Veejay’s Renovations means the structural engineering and energy performance goals get considered together rather than in separate conversations that never quite connect.
Fix Thermal Bridging Before You Close the Walls
Insulation inside the wall cavity doesn’t solve the problem completely. Heat will still take the path of least resistance and be conducted through studs and joists that connect the inside wall surface to the outside wall surface. This effect is known as thermal bridging, and it significantly reduces the overall insulation value and energy efficiency of the wall.
To minimise thermal bridging, there is a need for a continuous layer of insulation over the entire frame of the wall and around the doors and windows to maintain the thermal barrier. This will prevent heat from escaping the building and cold from entering. However, the installation of a continuous layer of insulation is challenging and requires extra material and labour costs. But since it leads to considerable energy savings in the long run, it is worth considering.
Build Your Roof For Solar Before You Need it
If you’re remodelling your roof and you know you want to have solar panels, an electric vehicle charging point in the garage, or a battery wall in the near future, this is the time to plan for it. These products require substantial weight and/or a penetrative connection.
If your remodel includes roof modifications, new trusses, an extension, or a second story, engineer the structure now to carry solar panels later, even if you’re not installing them immediately.
Solar PV systems have real weight, and not every roof structure is built to handle it. Specifying the load capacity and getting the pitch and orientation right during construction is a minor design consideration. Retrofitting structural support under an existing finished roof is a much larger job.
The same logic applies to battery storage. Wall-mounted battery systems are heavy. If you’re reconfiguring internal spaces, think about where that system would sit and whether the wall framing can take it.
Run Your Hot Water Pipes While the Floors Are Open
When you’re pulling up flooring and working on the subfloor, you have direct access to the space beneath your floors. This is the perfect time to reroute and insulate any hot water pipes that run across this space. This is particularly important for long runs of pipe that carry hot water from your heater to a distant bathroom or kitchen.
Uninsulated hot water pipes lose heat as they run through cold spaces. The longer the run, the more heat is wasted as water cools in the pipe and has to be reheated. Insulating hot water pipes is a cheap way to keep the hot water hotter, but unfortunately, getting access to the pipes is not.
Fortunately, you’ll already have that access, so take advantage of it and insulate those hot water pipes. The same goes for greywater diversion. If you’re considering rerouting the wastewater from sinks and showers to use in the garden to flush toilets, this is a much easier job if you can see and work on the subfloor.
The golden thread running through all of this is that structural exposure is expensive to create and brief when it arrives. Make sure you’ve planned your energy upgrades before the demolition crew shows up, not after.
DISCLOSURE – This is a collaborative post.
