In 2005, the Housing Authority launched a pilot energy-saving project at Tal-Ftieħ, Birkirkara. The aim of the project was to achieve better energy performance in building while promoting innovative measures that make the best possible use of natural resources without harming the environment.

Commenting on energy-saving housing, the chairman of the Housing Authority, Marisa Micallef, said: "When we launched this project we wanted it to serve as an example of good practice and to save our clients' money and energy. Our hope is that this is just the start of a journey, which will result in far more eco-homes all over Malta and Gozo, and that this would become mainstream over the coming 10 years. Obviously, we need to win the hearts and minds of clients and overcome the financial burden of building to energy-saving standards in the first place, but this project has shown that we can be green and should continue to be so in years to come."

The building block in Tal-Ftieħ was constructed to include energy-saving features, such as double glazing windows, louvers, roof insulation and 150-litre solar water heaters for each apartment, including pipe insulation.

A recent study showed that the solar heating systems operating since 2005 at Tal-Ftieħ each saved an average of 1,850 kWh of energy and 1.6 tonnes of carbon dioxide every year, excluding summer. This implies that the payback period for these systems would be about four years under real operating conditions.

Engineer Charles Yousif, of the Institute for Energy Technology of the University of Malta, together with an Erasmus student from Valladolid University, Spain, have carried out an independent study on these solar systems. Support was also given by Dr Vincent Buhagiar from the University's Faculty of Architecture.

Data collected ranged from six months to three years on four systems that were continuously in use by the occupants. Results showed that hot water availability depended very much not only on the correct installation of the solar system but also on the lifestyle adopted by the users.

Heavy users of hot water had to switch their electric back-up heating more often, while prudent users only switched on their back-up heating elements for the first time in December last year.

In fact, this month was exceptional for Malta, with rainfall totalling 206.8 mm, over the average for the month since 1922. It was found that average users would expect to switch on their back-up electric heating for a few hours every day for about 15 days a year.

In winter, the average hot water temperature in the solar tanks ranged between 50 and 60°C, while in summer, the systems had to be covered to avoid over-heating. This routine exercise of covering and uncovering the panels once a year also served the users as an opportunity to check their solar systems for any leakages or other visible defects.

The maximum overnight temperature drop of the solar tanks was found to be 11°C in winter, but since the overall water temperature was above the 50°C mark, the morning temperatures were still quite adequate (around 40°C) to provide sufficient hot water without switching on any electric back-up.

The study also showed that the minimum hot water usage of the occupants would be 20 litres/person/day, while a more typical usage would be around 30 litres/person/day for washing needs only. This is the first time that such figures were published, based on long-term monitoring of hot water usage.

Infra-red thermal images taken on site showed that the solar tanks and panels had excellent thermal insulation properties and no defective areas were found.

All in all, the solar systems performed very well during the first three years and the only maintenance that had to be carried out on some was the replacement of the electric back-up heating element, which seemed to deteriorate due to the combined effect of high temperature and salinity of water.

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