Why would anyone want to build, buy, or even live a thermally inefficient dwelling? Even in this day and age, the majority of people still do not understand the value of an energy efficient home. Those same people would shy away from purchasing energy guzzling V8’s or SUV’s but seeking to know the energy efficiency of a home makes as much sense to them as asking them “how many miles to the gallon does the home you live in get”?
This knowledge is not for everyone. This knowledge is only for those who seek it out or at the very least, open to listening to the “new wisdom” which has been practiced worldwide throughout history and I would wager even long than that.
The truth about using mother nature to reduce your electricity bills will set you free from wasting your finances on the need for excess energy consumption required for home heating and cooling that you never needed to pay for. I have said for many years that, “the most expensive kilowatt hour of electricity is one you didn’t need to buy in the first place”.
There is no shortage of information about “thermal mass” on the internet.
A simple google search advised of 266 000 000 results in just 0.41 seconds. It is defined online, “In simple terms, thermal mass is the ability of a material to absorb, store and release heat. Materials such as concrete, bricks and tiles absorb and store heat. They are therefore said to have high thermal mass. Materials such as timber and cloth do not absorb and store heat and are said to have low thermal mass”.
When my young family lived on the northern side of Brisbane, back before the turn of the century, we lived in a brick and tile home which were very common in most new estates. They generally had single skin brick walls on the outside, plaster board internal walls and a tile roof. These houses were found in that design in great multitudes as far as the eye could see.
With a slab of concrete on the ground, the bricking could be done in one day. A friend of mine was a building project manager for decades generally “handed over” 30 of these constructions for habitation each month. That’s one every day. In some months he may hand over as many as 33 in a month. He was only one of four other project managers working out of just that office and he didn’t work for the biggest construction company either. The houses were well built. Both his family and mine lived in dwellings built by the company he worked for. They were well built but very poorly designed. They were not designed to be energy efficient. They were designed to look good at an affordable price which are the main ingredients for achieving a quick sale.
As far as being energy efficient, they could almost not have been built any worse and one may even have considered that they were purposefully built to fail.
A concrete slab sitting on soil north of Brisbane will generally have a mean comfortable temperature of around 23 degrees. That’s comfortable. But putting a tile roof on a dwelling, this close to the equator with such sun exposure is “thermal suicide”.
Homes in this area with tile roofs are inherently hot during summer as they are exposed to relentless heat for the entire day during clear sky weather. This heat is stored and then radiated back into the house well into the night requiring a serious air conditioner to be running 24/7 for the season to make inside ambient temperatures even bearable.
If that was not bad enough, the single brick wall of these homes is on the outside where it is also exposed to direct sunlight which only exacerbates the unbearable temperatures.
But the houses looked good.
Unfortunately, they are almost unlivable during the summer unless you have aircon and a bank account capable of serving the cooling bills to make them livable.
I say they built the houses inside out. The bricks should have been on the inside.
If that had been the case, the bricks, having high thermal mass, could have been shaded from direct sun exposure even if that required the closing of the curtains during the day. The brick would then have limited to the ground temperature of 23 degrees and would have absorbed heat during the day keeping the inside temperature closer to the 23 degrees ground temperature and not closer to the 40 degrees outside temperature.
I am keener to be in an environment with an ambient temperature of 23 degrees than to be in an environment with an ambient temperature of 40 degrees or even -4 degree
If the roofs had been a lightweight material, that is, a material with low thermal mass, the heat of the day would not have been stored and re radiated out during both the night and the day. Yes, steel roofs do get hot, but they do not hold the heat and because they have low thermal mass, they can quickly dissipate the small amount of heat they may have very readily.
What is the benefit.?
You would have a home with low thermal mass on the outside that would be exposed to the sun. These building materials would not store heat and then re radiate it during the summer months.
You would have a home with high thermal mass on the inside to absorb heat during the day regulating the inside ambient temperature.
When the inside ambient temperature would drop below the mean temperature of the bricks, the bricks will relinquish heat lifting the temperature so that everything has the same mean temperature.
This concept works in the occupant’s favour both summer and winter.
We built our home taking advantage of these principles and we enjoy stable internal temperatures all year.
During the summer we leave the windows open at night to cool the internal bricks and we close up during the day keeping the heat out. There is enough thermal mass inside to keep inside the home close to ground temperature all day without any need for auxiliary cooling.
Exactly the opposite is experienced during winter months, so the laws of thermo-dynamics work for us every day keeping our internal temperature close to the “sweet spot” day and night in any season.
The placement of the correct materials with the ideal thermal mass in any building project is part of achieving the best thermal performance outcome of a building.
The thermal performance is determined well before construction starts, but, once a building has been constructed, the characteristic of its design is either enjoyed or tolerated for its entire existence.
You don’t get a second chance to get it right the first time. Knowing how to use the conditions of building materials with high or low thermal mass to your advantage is very advantageous. A smart rooster would not build, buy, or even rent until he had a functional understanding of the secrets of thermal mass.
A home that performs thermally well is not an accident and a house that is thermally comfortable in all seasons is a better home.
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Moreton Bay residents can access weekly tips from John on Community Radio 101.5 FM Friday Mornings at 10:10am
John Lynn