The importance of building insulation

The importance of building insulation

With ever increasing costs of energy, proper home insulation is essential to ensuring long-term comfort and value. In addition, floor insulation also has significant sound proofing benefits that add peace and quiet to a private residence or an apartment structure.

"Why Insulate" seems like a rhetorical question with an obvious answer: to save energy while providing long-term comfort inside a structure. However, what's not so obvious is that most homes are severely under-insulated -- either by design (to save building costs) or due to oversight in the design process. With escalating energy costs and increasing greenhouse effects, construction professionals have a responsibility to the end client -- as well as the environment -- to ensure that new designs reflect the latest insulation recommendations, even when these recommendations exceed the BCA (Building Code of Australia) requirements.

Thermal comfort

Insulation resists the flow of heat. Heat is a form of energy - it always travels from hot to cold - flowing outward in winter and inward in summer. By reducing heat flow, a properly insulated home uses less energy in winter for heating and less in the summer for cooling.

How much insulation is required depends on where you live and the expected temperature extremes. Insulation is identified and labeled according to its R-value. "R" is resistance to heat flow. Higher R-values provide greater insulation. Thermal energy moves from a higher temperature to a lower one, the bigger the difference the faster the transfer.

A radiant floor heating system is designed to radiate heat from heating elements installed below the surface of the floor. This is a low-cost, efficient way to heat your home. However, since the heat moves in all directions, not just up, some of this heat is wasted as it travels down into the slab or into the airspace below suspended timber floors.

Concrete floors

The specification of insulation for concrete ground floors is more complex than that for walls or roofs. This is because the mechanisms for heat flow are affected by the ratio of surface area to perimeter.

Suspended timber floors

With a suspended timber floor, there is little choice but to install the insulation between the joists, but the thermal bridges created by the joists have to be considered. The insulation must be cut to fit tightly between the joists to prevent heat loss.

Alternatively, installing reflective insulation across the joists will assist in reflecting back the previously wasted heat up into the structure, reducing the heating costs.

How quickly can I expect my heated tile floor to get warm with insulation?

This depends on a number of factors like the floor type and thermal insulation: a concrete sub-floor without an insulation layer below the floor heating creates a drag on the performance of the floor heating. A layer of quality thermal insulation such as Marmox will speed up the initial warm up times to within 15-20 minutes and reduce heat losses.

Do I need thermal insulation with a reflective surface?

Reflective surfaces will give a greater thermal insulation performance when an air barrier is present (like below a suspended timber floor). If buried within a cement layer then the reflective surface will act as a conductor and transfer heat or cold. No useful gain can be attributed to a reflective surface when applied in this way.

In conclusion

Insufficient insulation exaggerates temperature swings inside a structure, causing uncomfortable draftiness. Summer days feel hotter...and winters feel colder when a home has insufficient insulation. Furthermore, under-insulated homes can cost occupants hundreds -- or thousands of dollars a year in higher heating and air conditioning bills. These costs are wasted year after year and the energy is non-recoverable. Whereas spending a little more up front pays dividends every year as the incremental cost of better insulation is amortized over the lifetime of the structure.
 
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