Understand home heat loss and heat gain

How does Home Heat Loss and Heat Gains work?

Written by AAA Insulation on .

Understand Home Heat Loss and Heat Gains

It’s that time of year again when everyone starts running down to the shops to buy a new heater. Very few people truly understand the fundamentals of home heat loss and heat gain and understanding this might save you in the long run.

The laws of Thermodynamics

No matter what you, if it’s 5 degrees outside and 30 degrees inside, the cold will always try and suck the heat out of the home. We go over the basics of thermal insulation in our recent article here, but in this scenario, cold air is always trying to sneak inside through every little gap, nook, and cranny in your home. This is a process known as infiltration.

The reverse is true where the hot air is also trying to escape through every crack in your home. This process is known as exhalation. If you think about it, it’s kind of like your home is trying to breathe both air and temperature in and out.

The total of all this air leakage is called home heat loss and is measured by a heat loss rate in Btu (British thermal units) per hour. The point of insulating your home is to provide a thermal barrier to slow or prevent this rate of home heat loss.

Understanding Home Heat Loss

If your home is poorly insulated or there is damage to your home, the rate of heat loss might be quite high. This means cold air is easily getting into your home and warm air is fast to escape out of it.

Dampness, mould growth, and difficulty heating up the home are several symptoms that reveal a lack of insulation.

On the other hand, a well-insulated generally has a low rate of heat loss. Insulation provides a barrier that means your home will better retain its heat while being more energy-efficient.

Understanding Home Heat Gains

Your home’s inside temperature is affected by the actual outdoor temperature and humidity levels. Home heat gains come from the outside weather, all your electronics, heating sources, and even the people who live inside. Unfortunately, on a very warm day, it can become very uncomfortable to live in and you want to try and remove all this excess heat.

Cooling systems work to remove unwanted heat from a space and relocate it. This is essentially what a heat pump is designed to do. By using an air conditioning process that takes advantage of the relationships between pressure, temperature, and volume, we can extract heat inside the home and redistribute it outside while replacing it will cooler and dryer air.

Uninsulated homes are very difficult to heat. Heat gain’s in these homes typically far exceed the rate at which you can efficiently cool it down. Insulating your home provides a thermal barrier that is just as effective in the summer as it is in the winter. Insulation will help work slow the rate of home heat gains making it far easier to cool down your home and control your inside temperatures.

Your home heat loss and gain weak points

Now that you understand a little more about home heat loss and home heat gains, it’s important to understand where the weak points in your home are.

For a typical kiwi house, your roof accounts for 40-50% of your home’s heat loss in the winter. The roof also adds between 50-60% of your home’s heat gains in the summer. Installing decent insulation in your roof cavity is one of the most important things you can do for your home. Luckily, most homes have a fairly good level of roof insulation although sometimes it’s worth looking at topping this up, especially in older homes.

Uninsulated walls are the next large issue area accounting for 30-35% of your home’s heat loss. They also contribute between 15-25% of your home’s heat gains. Building standards have traditionally not been very good in New Zealand. Many older New Zealand homes won’t have any wall insulation. A lack of insulation is the primary cause of damp walls and wet windows. We highly recommend you resolve this issue as soon as possible.

Next up are your windows, as much as 20% of your home heat loss and gain happens through your windows. Upgrading single pane glass windows and joinery to double glazing is a great way to solve this issue and fix this part of the home’s thermal barrier.

Finally, underfloor insulation can prevent as much as 10% of your home heat loss and gain. It’s not always possible to add underfloor insulation to your home. Homes built on piles provide a gap to install polyester blankets under the floorboards. This can help complete the home’s thermal envelope.

Talk to an insulation expert about your home heat loss and gain.

If in doubt, it’s always best to discuss your home insulation needs with an expert. Talk to the team at AAA Insulation today to find out more about how to fix your home heat loss and gain issues.

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