Category: Passive Solar

Thermal Mass for Heating

If you read up about energy efficiency you will come across the expression ‘Thermal Mass’ . . . . . . but what is it? . . . . . and how does it work?

Materials with Thermal Mass

The most common materials with Thermal Mass in new houses are; Concrete, Stone, Slate, Tiles and Brick. In some cases water tanks can also be used to provide Thermal Mass. (But not easy to use as evaporation can  reduce the effectiveness, and the resultant humidity can cause damp)

A key characteristic of these materials are they are dense(heavy) and have the ability to absorb excess heat and then release it in cooler periods.

Thermal Mass need to be exposed. Covering with carpets or timber floors insulates them and prevent it from being as effective.

Heating

The trick is to put either ‘Free  or Low Cost Heat’ or ‘Spare Heat’ directly into the thermal mass which is released to keep your house warm longer.

Free or Low Cost Heat

Direct winter sunlight on a floor or a wall is a great source of free heat.  Just make sure you have Properly Designed Shade to keep the summer sun out.

Sources of low cost heat are things like using off-peak power, or excess solar power.  This can provide either direct heating, or run heat pumps circulating hot water into a slab.

Spare Heat

Each time a wood heater is filled with wood  it should initially be run with the vents fully open to minimise build up of creosote and soot in the flue . Without a thermally massive surround to help absorb the excess heat you can quickly over heat your room.

Any exposed thermal mass that is not heated may feel cool to the touch as it will be no warmer than the room temperature. However as the room cools this thermal mass will still release its heat back into the air to slow down the rate the room cools down. (This is known as ‘Thermal Lag’).

See Passive Solar for more posts

Glaring Fail

Here is a new town house development in Melbourne.

Just a couple of ‘small’ problems

  • Those huge master bedroom windows face west so they are going to get the summer sun all day from around 2.00pm until late in the evening.
  • What makes it worst is it has full length mirrored wardrobes on the North Facing Wall

With the glare you will need to be wearing sunglasses just to go into the room. On a hot day it’s going to be around 60 degrees plus!

 

For more Fails and unusual houses go to What the………….?

 

Advice – Fail

When I saw this Billboard the other day I had turn round to drive past it again, as I didn’t believe it the first time!

They are making it appear that it’s a big deal that they are selling what are the worst blocks on the estate!

A North Facing Block mean that the house gets very little warming sun during winter, as half the front of the house will probably be garage door.

A typical house will also have lots of East and West facing windows which will really soak up summer sun making the house a real sweatbox. With winter there will be no sun coming in but lots of heat going out through those windows.

It just goes to show that if you want honest advice don’t rely on Real Estate Agents or Land Developers.

 

To find out which way to face is best see Orientation

For more fails and unusual houses go to What the………………….?

 

Block Orientation

Sponsored by Coral Homes

When looking at block orientation a key issue is using the sun to warm the house in winter and keeping the sun out of the rooms in the summer.

Typical blocks in Australia are rectangular. About twice as long as the block width, as are most home designs. This limits the way you can place the house. In my experience the order of preference of blocks is.

1. Facing East
2. Facing West
3. Facing South
4. Facing North

If you have got a block at an angle it will require a bit more thought unless you can orientate the house in one of the above preferred directions. Larger blocks and square blocks make adjustments to the house orientation easier.

My reasons for the preferences are as follows:

Facing East

This orientation allows one of the long sides to face north making the best use of the sun in a passive solar house. Usually the master bedroom is at the front so even in the summer the low sun morning sun only warms the bedroom from the chill of the night. Windows can be minimised on the west side to stop the house overheating in the afternoon and evening. This orientation also gives you plenty of roof area for the most effective location of solar hot water and solar electricity panels.

Facing West

Again like the east facing block you can have one of the long sides to face north making the best use of the sun in a passive solar house. With a master bedroom at the front you will need to take steps to keep the afternoon sun out of the room to stop overheating. Like the East facing orientation this is useful for solar panels on the roof.

Facing South

With a house facing south the best layout is to have as many rooms as possible having large windows facing north which can be difficult on a narrow block. To make the best of this orientation you may need to have plans drawn up as most standard plans don’t suit this orientation. It’s also best to minimise west facing windows.

Facing North

A north facing house is probably the least desirable on a suburban block as it makes it hard to get the sun into the house. I certainly wouldn’t want big north facing windows allowing passers by to look in.

 

Lots more information in the anewhouse Guide to Buying a Block for only $4

See similar posts see Choosing a Block and Passive Solar

 

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