Everyone wants to live in peace and comfort, and one of the most important ways you can ensure that is through the thermal performance of your home. Your windows and doors play a crucial role in the temperature and overall contentment you feel at home. Here are the key things you need to know to understand thermal performance.
What is thermal performance?
Thermal performance is the measure of a building’s ability to retain or resist heat, and in turn maintain a comfortable temperature, while using minimal energy. In practical terms, it refers to how much cooling or heating a building requires to feel comfortable inside. Buildings that require less heating or cooling have better thermal performance because they use less energy.
The Nationwide House Energy Rating Scheme (NatHERS) uses a star rating system to measure thermal performance, with buildings ranked from 0-10 stars. More stars means a higher thermal rating, which means the building is more efficient. All new buildings in Victoria are required to have at minimum a 7-star rating, which means that it requires some heating and cooling, but is decently efficient.
Though it’s important to understand the efficiency of the whole building, our focus at Miglas is more specifically on the performance of our windows and doors, instead measured by WERS.
Window Energy Rating Scheme (WERS)
Managed by the Australian Glass and Window Association, WERS is an accredited system for testing and rating the energy impact of windows and doors. Each piece is given its own WERS rating and label, which rates its performance in several key metrics, including:
U-value (Uw): A measure of insulation, and how quickly heat can be transferred through the window or door, either escaping the home during winter or entering it during summer. Better insulation means heat takes longer to transfer, which creates a lower U-value.
Air Infiltration (AI): Indicates how much air will enter through a product, with a lower AI value meaning better performance. This ensures greater control over the indoor temperature and comfort.
Solar Heat Gain Coefficient (SHGC): How much heat (or solar radiation) passes through a window or door. A lower SHGC means less heat passes, which leads to a cooler interior temperature.
Visible Light Transmittance (Tvw): The amount of visible light able to pass through a window or door. Natural light affects both warmth and the need for artificial lighting. Higher Tvw means more natural light.
WERS ratings take all of these measures into account and provide an indicative percentage of how much better the product is for heating and cooling compared to a baseline product. Finally, the label includes an overall 1-10 star rating, with more stars meaning better performance in keeping the inside of a building comfortable.
Why is thermal performance important?
Optimising the thermal performance of your windows and doors has a significant impact on your everyday comfort. The Australian climate varies greatly in different parts of the country, and Victoria in particular is characterised by hot summers and quite cool winters. Better thermal performance means that, regardless of the outdoor climate, your indoor temperature will stay pleasant either through heat retention or reflection.
Outside of that, thermal performance can also save you a lot of money. If your home is more energy efficient, it’ll require less heating and cooling to stay comfortable, which drops the price of your energy bills. You can also rest assured that you’re contributing to a more sustainable environment.
Main factors that affect thermal performance
To understand how different aspects of the home affect thermal performance, it’s worthwhile to look at the three main types of heat transfer:
Conduction. Heat moves through solid objects, like walls, roofs and floors. We try to manage this type of heat transfer through insulation.
Convection. Heat moves through the air, and we try to manage it through ventilation.
Radiation. Heat moves through electromagnetic waves, or put more simply: sunlight. We try to manage this transfer through shading and window treatment.
Having high quality insulation, ventilation and shading will improve your home’s thermal performance, allowing you to better control your internal temperatures. These factors ensure you can keep hot air in during cooler months, and keep it out when it’s warmer.
Another key factor is the layout of your home. North-facing windows are able to capture more sunlight and warmth in the winter, keeping your home well lit and warm, and can be effectively shaded by eaves in the summer.
Choosing the right windows and doors
High-performance windows and doors can improve energy efficiency and save you a lot of money, but if you’re relatively new to the game, what exactly should you be looking for in your products?
Double glazing
Consisting of two glass panes separated by a sealed gap, double glazing improves insulation, leading to less heat and sound transfer. This not only makes your homes quieter but also ensures less heat is lost when it's cold outside, and less makes it in when you’re already sweating. It’s a great investment to reduce your energy bills and keep you cosy.
Low-E coating
Low-emissivity coating is a thin layer applied to glass that allows visible light to pass through while reflecting external heat away from the home, and reflecting internal heat back into the home. It reduces your costs, ensures you don’t lose natural light, and protects your furniture from potential UV damage
AliClad
Using a timber frame with a durable aluminium exterior, AliClad is extremely durable, stylish in appearance, and extremely energy efficient. Our trademark AliClad range is purpose-built for Australian conditions, combining the maintenance-free benefits of aluminium with the superior insulation and appearance of timber. AliClad windows and doors also have an extremely long lifespan, with most products lasting for more than 60 years without needing to be replaced.
How to improve thermal performance
There are a lot of ways to improve thermal performance. The first is to look at adding insulation in your walls, roofs and floors, which will help you manage heat transfer between indoors and outdoors. However, you should be wary of adding too much insulation — this might mean you need to constantly climatise inside because no warm air can get in or out when you want it to.
Building owners should try to reduce air leakage by fixing cracks and openings, and consider adding blinds, awnings, shutters and external shading. Choosing electric appliances — including HVAC, lighting and kitchen appliances — with higher energy ratings will also improve thermal performance.
Finally, consider the height of your windows and doors. Taller windows typically allow more daylight, but they also let in a lot more heat, requiring more air conditioning or wider eaves and shading. A well-designed balance between height and shading can ensure efficiency throughout the year. We are happy to consult with you on the best design choices.
Improving energy efficiency at home with Miglas
Better thermal performance means better energy efficiency, which saves you money, protects the environment, and helps you live in comfort — and creating comfortable, sustainable living is at the core of what we do at Miglas. Our premium product range and customised solutions are all designed to improve thermal performance without sacrificing aesthetics.
Explore our entire range of high-performance windows and doors, or get in touch to find out how our commitment to energy efficiency can give you more comfort at home.
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