I see most people make the same mistake when they’re trying to build a sustainable, net-zero, or low-energy building:

They’re overwhelmed by the options and products available to them. And they can’t tell them apart, because every product (and sales person) claims to be the silver bullet in making your house energy efficient.

So some get hung up on a particular product that they personally resonate with. Others think they need to put every single one of these marketed products into their house to make it energy efficient. And making a decision becomes really hard after a while.


Because when you go to an expo, there are hundreds of products on display, and all of them say they’ll “reduce your energy costs by 25%”. Next, you visit some places on Sustainable House Day… and while at one house they did X, Y & Z, and swear by what they did… at the next house they did A, B & C, and say there is no better way to do it. And when you talk to your neighbour, he swears that he heard that painting your roof with yoghurt can help increase efficiency by 22%. The arguments, sales pitches and opinions just keep piling on and on… until you are fed up and make a decision to stop your brain from melting:

You sign a contract, make the order, and end up spending tens of thousands of dollars on a variety of solutions that promise to help your building become more energy efficient.

But there is a problem: You don’t find out if the house is naturally warm, or a bit chilly, or even ‘energy efficient’, until you actually live there. And by this time, it’s too late: The house is built. And it would cost you even more tens of thousands to make the changes needed to get your house to where you want it to be energy wise.

How the architects and builders build their own homes…

Now, let me tell you how people “in-the-know” do it:

Like most other people, they design the building with energy efficient and solar passive principles in mind: Good shading in summer. Insulation where it’s required. The right type of glazing. Ventilation. Winter solar gains.

That’s the obvious part…

But then they take it a step further (and that´s where “the secret” of truly sustainable houses comes from):

They have an engineer perform energy modelling on the building design with special software. Before anyone even comes close to a saw, shovel or a drill.

What does this mean? I’ll give you a quick run-down…

Step 1: The specifics of the building design are precisely input into the software

What the walls are made of, how many levels there are, the size of the windows, the precise type of glass used, overhangs and shading over windows or walls, how the floors are constructed, how the roof is built, etc.

For example, let’s consider this roof construction: “Surf Mist Colourbond” mini-orb, with 75mm anti-con insulation under, 500mm roof space, 190mm thick bulk thermal insulation, 10mm plasterboard ceiling). (That’s right, even the colour of the material is taken into consideration. )

All of this information helps determine the thermal resistance of each part of the building. In other words, we know the precise R-value of each part of the building. The roof, the southern double brick wall, the western reverse brick veneer wall, etc.

Step 2: After this, the building’s location is input (e.g. Swanbourne)

This lets the software calculate the exact position of the sun. It knows the expected temperatures throughout the entire year. It even knows the prevailing wind direction and speed.

Step 3: Software does it´s calculations

The software is then told the orientation of the building (how the building is positioned in relation to ‘North’) and then it can start doing its´ magic. And it does this ‘magic’ for every hour… of every day… for an entire year.

At the end of the simulation (Step 4), it has run thousands of scenarios for the exact building design, in the exact location it’s going to be built. And it shows PRECISE figures of how much energy is infiltrating and escaping the house at different times of the year.

Why is that important?

Let’s consider the Living Room of a new house design in Swanbourne. The software will tell us that on January 27th at 14.00, this room has the highest heat gains for the whole of the year. Higher than at 15.00. Higher than on January 28th at the same time. It will show us that precisely 10.32kW of heat is entering the room, and this is the highest it is during the whole year.

Now this is great information to know (from this you can precisely size your heating/cooling system, meaning no mistakes).

But the real value comes from further analysing the data (Step 6):

Upon analysis, we might determine that 6.11kW out of the total 10.32kW of this January heat gain is coming through the main northern glass sliding doors in the Living Room. We know which direction it’s coming from, the precise angle, and how much heat it’s introducing… and then (and only then) can we can really decide if it makes sense (in terms of finance, energy and comfort) to do anything about it and what:

In this case, we might recommend extending the overhang, or introducing a shading-screen, cutting this 6.41kW out. As a result , we’ve now reduced the summer heat gain from 10.32kW to 4.21kW… a 59% reduction in unwanted energy gains! This applies in winter too (but in reverse – to reduce heat escaping the house)… and spring… and autumn (it might seem strange, but some parts of buildings will experience the highest heat gains in Autumn).

As you can see, this was a simple change that reduced the heat gain by 59% and you didn’t have to use any fancy (and expensive) products or materials!

The most important step is…

The most important step in making your house sustainable and energy efficient is therefore NOT buying the latest, most advertised product/material/technology… but reducing your energy loads from the get go. (Yes, we are a little unpopular among the building material sales people for exposing this. There is not much profit in using nature and it´s behaviour to do the cooling/heating for us.)

Once you have this final, scientifically calculated figure, you can now truly decide if that top-of-the-range-wifi-controlled-system is truly worth it. If that underground rainwater tank needs to be that big. If the floor heating/cooling system should be that extensive. Or if you should pay for the extra few kW of PV panels.

Now, you’re probably asking “Why, if it makes so much sense to do these calculations, doesn´t everyone do them? Or are they that expensive to perform?”

Well for example, for a ‘medium’ size house it will cost approx. $2400 to perform these calculations (but it can range from $1200 to $3600 based on building size and complexity).

So, if you are planning to build (or renovate) your home and make it a truly sustainable one, select someone (and at Euroheat we will be glad to help) who will not only sell you as much building work and material as possible, but someone who will do these calculations so that you can make a decision based on numbers and facts… so that you’re not unpleasantly surprised when the house is built and it´s too late to make any changes.

And if you decide you want to achieve these results in your sustainable house too, we can help you:


  • Thermal Energy Modelling: We’ll use special software to comprehensively model the heat gains and losses of your building during the year. From this we know how well each part of your building performs thermally… or underperforms. And this means we can make the necessary design changes before your house is built. It might be to increase the insulation in the roof. Or change how the glazing is shaded on the northern aspect. But one thing is clear – we will have precise, calculated data. And this means you (or us on your behalf) can make quality informed decisions on what to do with your building.
  • Building Design Details: Want to do it like the pros in Europe? We’ll explain to you and specify the exact kind of insulation that’s best for your building, and how it should be installed with detailed drawings. Or we can detail how to get your building airtight or solar passive (without breaking the bank). All in-house by our engineers and architect.
  • HVAC Design: If you’re after an integrated HVAC system for your building that’s guaranteed to work, based on our 25+ years of installations, and professionaly engineering knowledge, we can help you. We’ll expertly design an integrated heating and cooling system for your home, which will include:
    • Floor/wall heating/cooling
    • Aircon heating/cooling
    • Fresh air ventilation
    • Pool heating
    • Tap hot water heating
    • Photovoltaic & battery system

Detailed calculations will be performed and precise plans drawn ensuring your system is guaranteed to work, and work at peak efficiency.


  • Hydronic Floor and Wall Heating & Cooling: We will expertly install your floor or wall hydronic system to the highest of European standards. Each pipe will be well insulated where it should be – meaning no needless energy losses. The pipes will be the right size – meaning the energy is delivered and well transferred to where it needs to go. They’ll be positioned only where they will provide benefit in your building (and not waste you money). And most importantly, every single metre of pipe is tested, making sure there will not be any problems in the future, and they will service your building well for at least 50 years.
  • Fresh Air Ventilation: Keeping the air quality in your house high is super easy. We will monitor the CO2 levels (so we know precisely when fresh air is needed). And we can mix in this fresh air either with your aircon, or supply it direct. Even a dedicated heat exchange ventilator can be used to exhaust the stale indoor air and supply fresh outdoor air (without losing much thermal energy). All you’ll see is some good-looking grilles that we install in the ceiling, and you’ll feel the benefit of fresh air.
  • Integrated Hydronic HVAC: You don’t need to have 10 separate pieces of equipment for the services in your house – we’ll combine them all into one for you e.g. combined floor, air, pool, hot water system). Why? Because this way you not only save space, but you dramatically increase the efficiency of your services by having them work together (and not against each other).
  • Thermal Insulation: Did you know that even if you install thermal insulation to your house, your energy bills can still be sky-high? That’s because of two reasons – the first is that if the insulation is installed poorly (gaps, airflow between, compressed or dusty) it can effectively null the performance. The second is, not all insulation products are as good as they’re touted (e.g. foil and blanket insulations). Due to technicalities, they are allowed to state their performance as higher than it actually is in any real-life application. But we’ll only recommend to you what we know works (based on the laws of physics). And we’ll install it so that it works to its best ability – no gaps or holes that will leak energy.
  • Off-Grid: Modelling of your building’s energy use lets us size and design a PV and battery system that allows you and the rest of your building to operate all the lights and appliances you want… without drawing energy from the grid. We’ll properly size and install the system so you have power when you want it, and most importantly, when you need it.
  • Building Management Controls: Having exact oversight and precise control of your building services allows you to properly manage not only the internal environment, but also your energy consumption. We will design, program and install a customised building management system to help you create a low-energy or net-zero building. All of your building services, such as heating, cooling, ventilation will be included, along with your hot water services, photovoltaics, and even blinds & lighting.

The best thing is, we will monitor and optimise your system over the first year of running – meaning you truly will achieve efficiency.

  • Custom Heat Pump: Often an off-the-shelf heat pump doesn’t cut it…. They just can’t do everything you want them to do. So a long time ago, we started to build them for our clients, to their exact requirements, meaning it does what they want, when they want it, super efficiently. Want a super quiet heat pump? No problem. Want a multi-stage heat pump? Great, we have your back. We’ll make it happen for you.

What next?

If you’d like to build a truly sustainable home and create a totally natural feel and comfortable climate in it, give us a call and we can have an introductory quick 15 min. consultation over the phone with you about your plans. To help you understand the process. To help you select the right building products or HVAC systems. And to answer any questions. We promise no salesy pitching, just info on physics, energy flows, thermal efficiencies and how to use it all in seamlessly heating/cooling your house… 08 6468 8895

If you´d like to get our detailed expert opinion and guidance, please see our expert consultation option here.