The Homes Thermal Envelope

Fully insulating your home and its thermal envelope

The Homes Thermal Envelope

You may have come across the term ‘thermal envelope’ before, but what does this mean and why is it important to your home? In this article, we discuss your homes thermal envelope and how choosing the right insulation improves its effectiveness.

What is your homes thermal envelope?

In simple terms, your homes thermal envelope is a barrier that separates the outside air from the inside air. It’s made up of all the different products and materials that go into constructing your home. There are few important items that make the most difference.

Home heat loss occurs when there are gaps or weaknesses in its thermal envelope. These gaps or weak points are where heat can most easily enter or leave your home. The most common sources of home heat loss are your windows, doors, walls, roof and floors. Improving your home’s thermal envelope means improving the thermal resistance, or R-Value of these areas. Homes with a good thermal envelope are easier to heat and cool, are healthier to live in and are typically more energy efficient.

The core parts of your Thermal Envelope

Choosing the right windows and doors for your home impacts your thermal envelope.

If you’re living in an older New Zealand home, you may find that your windows only have a single pane of glass. This only provides a thin separation between the inside and the outside air, and one which heat is easily able to escape through. This is an example of a weak point in your home’s thermal envelope.

There have been great advancements in the design and manufacturing of residential joinery units over the past decade. Newer joinery units are double glazed and have much better thermal performance however in some cases you may want to go even further. Spending a little bit extra on your windows and doors can greatly improve your thermal envelopes effectiveness.

Adding argon gas in between the glazing units is a way to improve the performance of your windows and doors. Additionally, upgrading to triple glazing units, or adding window tinting are great at reducing heat transfer. All these options help improve your homes thermal envelope.

Wall Insulation

Up to 35% of your home’s heat can be lost through its walls. Well insulated walls are a big part of completing or improving your home’s thermal envelope and one of the areas that are most overlooked.

Adding Wall Insulation to your homes thermal envelope

Wall Insulation can be retrofitted to older New Zealand homes without the need to remove the linings. Insulation Is installed through small holes drilled from the exterior or interior. Once completed, the holes are easily repaired and repainted. One of the benefits of blown wall insulation is the ability to achieve high installed r-values which makes it perfect for most South Island homes.

Typically, only minimum levels of wall insulation is installed in walls. It’s worth talking with your builder about upgrading the wall insulation to high performance insulation products. This won’t add too much cost to the build, and you’ll quickly see a return on that investment through the energy saved from having a good thermal envelope.

Don’t forget about your floors.

Up to 10% of your homes heat loss occurs through the floors. Many New Zealand homes have little to no insulation under the floorboards. It’s important to have a moisture barrier that separates the ground from your house. Uninsulated floors are one of the causes of dampness in the home which creates an unhealthy living environment.

Thankfully, it’s easy to insulate your floors. Polyester insulation blankets and a polythene moisture barrier is appropriate to install under most floors. This helps to seal the underside of your thermal envelope.

As technology and products have developed, it has also become possible to blow high performance insulation under the floor. Warmafloor is a good example of an insulation product that can be blown between the floor joists in your subfloors and mid floors. In most cases, blown insulation provides greater R-Values than other types of underfloor insulation.

Having adequate insulation under your floor is vital to completing your homes thermal envelope.

Finally, make sure you’ve insulated your roof.

Your roof is the most important part of your home’s thermal envelope. In fact it can account for as much as 60% of your homes heat gains and 50% of your homes heat loss.

Roof insulation seals your homes thermal envelope

Even on overcast days, sunshine heats the roof and it becomes scolding hot. This heat often transfers through the roof and tries to enter the home creating an oven like effect inside. A well-insulated roof is an important barrier at slowing and significantly reducing the heat that can get inside the home.

We’re excited to see that government has recently announced new insulation standards which takes effect early next year. In some cases, this more than doubles the previous requirements taking the new minimum roof insulation levels to R6.6.

These changes will be great for New Zealand homes. The new standards will help bring home energy use down and also create warmer and healthier living environments.

Would you like to know more about your homes thermal envelope?

If you have any more questions or would like to have a chat about insulating your home, contact the team at Absolute Energy today.

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