For every square metre of sunlight falling on a Maltese roof, the equivalent energy supplied by the sun is approximately 1KW of energy (1000 watts per meter squared) depending on the angle of the sun perpendicular to the roof’s surface (time of day) and the cloud cover. This energy causes the heating up of the roof and hence your home.

A simple remedy is to use appropriate roof paint, either white or silver. As the paint gets dirty with time its reflecting effect is reduced, hence the roof must be cleaned to remain effective. Silver paint may also degrade with time and there is a tendency for it to darken in colour, thus absorbing heat rather than reflecting the heat away.

A more appropriate and slightly costly method is to install insulation on your roof to block out the heat coming from the sun. Roof insulation not only eliminates problems caused due to weather, like leakage etc., but also increases significantly the thermal and acoustic insulation of the ceiling.

Roof Insulation has a dual advantage, as in summer the ceiling remains cool, and radiates this cool air down, keeping your house cool. This helps in reducing electric bills significantly, since you will not need the AC too frequently. During winter, the insulated roof radiates less warmth to the outside, thus keeping your house warmer and further contributes to your electric bills savings.

A more costly method is to use an array of Photovoltaic (PV) panels which will shade your house from the hot sun and will convert about 15% of the energy falling on the panel into electricity. A PV panel works two fold, as it will provide shade to the roof and converts the energy incident on the panel into useful electricity.

Another technology which is approximately as costly as PV panels combines both insulation and flexible PV panels in one installation. This technology consists of a special insulating material which incorporates photovoltaic cells in its structure. Using this setup one will benefit from insulating the roof, create shade and produce electricity all at once.

Note that this technology has a lower efficiency in generating electricity when compared to the PV panels mentioned previously (approx. 12%.).  There is in turn an added advantage of not having a cluttered roof and can therefore walk on these insulated panels and still make use of the roof space. Obviously the shade you create when on the roof will reduce the electrical output of the inbuilt panels.

As a conclusion, insulating your roof will be a good energy saving method which would be cheaper than having one of the PV installations mentioned above, but you would not be generating any electricity and then feeding it back to the grid to further reducing your electricity bill. It is a matter of the best compromise between the technologies and what you can afford to invest in for the future.

Roof thermal insulation material applied to domestic premises may also qualify for a   grant of 25% on the purchase price and subject to a maximum of €232.94. More information can be found on the MRA website.