Build An Energy Efficient Home: Insulation, Glazing, Draught-Proof and Thermal Mass
(video, photos and texts courtesy of Trade Secret)
When there is a difference between the indoor and outdoor temperature, it creates a heat flow. The greater the temperature the greater the heat flow. In winter heat will be lost from the building and in the summer heat will be gained.
To reduce the heat transfer, its crucial to have insulation in the roof and walls.
It’s also beneficial to insulate timber floors. Insulation slows down heat gain/loss throughout the year. The R value is a measure of how insulation will reduce heat flow. The higher the R value the better the performance. A system R value can be obtained by adding R values of different materials. The R value of the insulation itself is called the added R-value.
Getting the glazing right is crucial for insuring indoor comfort. Look at the U-value on the Window Energy Rating for Windows scheme.
The lower the U-value, the better the insulation. Other labels such as the SHGC, which we talked about in our last blog post “Glaizng, Shading and Building Orientation Keeps Summers Cool and Winters Warm” is also important. Do not base your decision on U-values alone. Frames are important too. Choose only timber frame and aluminum frame with thermal break, which is a layer of insulation to reduce heat transfer through the frame.
A well insulated house is of little use if it’s not well sealed. The air inside a leaking house gets replaced every few minutes, or 20 air changes per hour. Make sure you have good seals on doors, windows, chimneys, exhaust bands, etc.
Allow cross-ventilation by having openings on the opposite sides with minimal construction inbetween. But ventilation can’t cool a building on hot days, so it’s important to have insulation and drought proofing to keep heat out. This reduces energy needed for air conditioning.
With a well-insulated, ventilated and well-sealed home, thermal mass can even out maximum and minimum temperature inside the building over 24 hours.
Mass does not create heat, it just stores and releases it. In winter you need mass to be exposed to sunlight. It will store the heat during the day and releases it at night when heat is needed. In the summer, shade the mass from the sun. Mass absorbes heat from the air, keeping temperature down during the day. Heat is released at night and can be flushed out by cool breezes.
Therefore, to design and build a comfortable home, remember the following points:
1.insulate and glaze to reduce heat gain/loss
2.use seals to prevent draughts, provide cross opening for ventilation
3.use mass to even out the temperatures.