Building Green - It doesn’t have to cost the earth!

Passionate about eco-friendly home design? Borland Architecture director, Roger Borland shares his vision of the ultimate carbon-neutral home.

There’s a growing realisation in Australia that our actions are without question having a detrimental effect on our environment. Despite our government’s attempts to reassure us that all is well and that coal is good for us, we seem to have moved past that draconian position and realised that we must do more to firstly slow down climate change and then hopefully reverse it. We owe it to our children to look towards the future and ensure the earth we inhabit will remain beautiful, healthy and full of all the biodiversity which we’ve taken for granted.

As building designers, we feel we have a central role in improving the built environment, especially when you consider the building and construction sector accounts for 36% of all global emissions. There’s a growing list of countries around the world that have now committed to being carbon neutral by 2050, but to date, not Australia.

Well, what’s the solution? The answer is multi-layered and complex, so I’ll address just one part of the problem in his post for simplicity’s sake: the energy usage of our homes.

Having a home that runs carbon-neutrally isn’t a simple task, especially if you try to do it with a building that complies with current standards. You’d need to use 100% green energy for the life of the building. The good news is that renewable energy is now either comparable or cheaper than fossil fuel energy, so the first and most important step toward creating an eco-friendly home design is to make the switch.

The next thing you should think about is how your new house can be more efficient. The less power you need in order to run your home, the lower your bills and the lower your footprint. Let’s break down our energy consumption and see what can be done.

When you consider that 40% of your power bill goes towards heating and cooling, that’s obviously a good place to start. It’s actually possible in Melbourne to design a home that does not require any heating and cooling. I will explain later how this can be done, but for now, let’s assume we manage to achieve that.

Next up, 21% of our power bill goes on water heating. Given we have no fossil fuels in our proposed home, we’ll need to heat our water using solar and/or a heat pump.

Other electrical appliances use around 19%. Ensuring that these appliances are as efficient as possible goes a long way towards creating an eco-friendly home design. By using smart technology, you can turn appliances off when they’re not being used.

Lighting uses 6% of your power. Designing your home to make the most of natural daylight and installing energy-efficient LED lighting will make a huge difference.

Refrigeration utilises 6% of your power consumption. Using highly efficient appliances is the way forward.

5% of power is used for cooking. Using highly-efficient induction cooking will allow for the removal of fossil fuels and reduce energy load.

Standby (yes, the little red light on your TVs and other devices), costs 3% of your bill. You can install standby power controllers which automatically switch off your appliances when not in use. With TV now streaming, you have all your programming on-demand, meaning there’s no need to record anything, so no reason to keep the TV on.

So we have increased our efficiency, changed our power supply to green electricity, captured power on-site and purchased the rest from a green supplier. Anything leftover, we offset.

Let’s go back to the heating and cooling for a closer look at how we can achieve a carbon-neutral solution. There are various proven solutions both in Australia and around the world. The best method for moving toward a truly eco-friendly home design is a voluntary standard called Passive House. The principles of Passive House are fairly simple to understand.

Airtightness

To control the internal temperature of the house, it’s important that it remains consistent and the air doesn’t mix uncontrollably with outside air. In Melbourne, we get huge temperature shifts, often from one hour to the next. Having an airtight building envelope helps to ensure the fluctuating outside temperature doesn’t have much effect on the conditions inside. Air changes are controlled through a specially-designed mechanical system delivering exactly the right amount of fresh air mixed with captured and recycled heat to maintain perfect conditions. Windows and doors can still be opened to suit individual comfort levels. We have been implementing stringent airtightness standards into our homes firstly by testing and recording where we can improve construction detailing on our Keam house. The lessons leant through his process have been invaluable and we have taken these principles one step further on both the Stacpool and Polo houses, both of which are proposed to implement many of the standards set out by the world-renowned Passive House standard.

Insulation

Like putting on the right clothes, insulation creates a thermal barrier between the inside and the outside and is the other critical ingredient in controlling temperature variations. It’s critical that this insulation is of high performance, continuous around the whole building fabric and installed correctly.

Really High-Performance Windows

Windows are typically the lowest-performing element of the building when it comes to maintaining heat or coolth, so it’s important to install windows that are designed to perform to a very high standard.

Thermal Bridges

This is when you have an element of the structure or building fabric that continues from outside to inside without an insulation break. This connection allows the structure to conduct heat or coolth from one side to the other, often creating condensation that causes mould and loss of performance.

Orientation Using the natural environment, and controlling it to maximise its advantages and minimise its disadvantages, is critical to making any homework, especially if you aren’t proposing to heat it and cool it using other means. Here is a great video that will explain the overall principles better than I can:

Of course, to be completely carbon neutral and create a truly eco-friendly home design, you also need to consider the embodied energy of the materials, transport and power used to construct the home in the first place. You then may also consider your lifestyle and what you can do day to day to reduce your impacts. I’ll cover these areas in future posts.

Borland Architecture has applied to become a Passive House Certified Designer in 2021, giving us the skills and expertise to design your house with accreditation to these high standards.