Refurbishing heritage buildings with BIPV, heat pumps, energy efficiency

A Swiss consortium has refurbished a church built in 1965 and located in Mollis in Canton Glarus with rooftop PV, new windows, insulation works, and heat pumps.

The heritage building was consuming 80,827 kWh a year and needed retrofitting but there were restrictions on changes permitted.

The six Swiss companies forming the consortium added new thermal insulation for the roof, walls, and basement deck, triple-glazed windows, heat pumps, and a south-facing roof-integrated PV system that supplies almost 50,000 kWh of solar power per year.

Now, the church’s energy consumption, including the heat pumps, is just 33,100 kWh, or 41% of its former requirement, enabling an excess of 16,200 kWh to sell into the grid.

The PV modules and mounting system were supplied by 3S Swiss Solar Solutions, a module manufacturer that recently expanded production with a new 250 MW line. In total, over 600 building-integrated PV (BIPV) modules of varying sizes were used. The bulk was from its MegaSlate product line, which has since been upgraded and renamed TeraSlate, along with 110 custom-sized modules made to match the shape of the roof.

“For buildings that need conservation and protection, our BIPV panels, either in color or black, are a chance to improve the energy efficiency and at the same time preserve the aesthetics or even enhance them,” 3S Swiss Solar Solutions, CTO, Marcus Bäckmann told pv magazine.

“We are seeing these projects on the increase in our pipeline” said Bäckmann. “It is important that heritage buildings also undergo an energy makeover and are not excluded from improving energy efficiency, reducing CO2 emissions, and being able to produce their own electricity.”

The Norman Foster Solar Award is given to so-called “plus energy buildings,” specifically buildings that produce more energy than they need on average for heating, warm water and electricity supply with the excess sold to the public grid. It is administered by Solar Agentur, a non-governmental organization that promotes solar energy in Switzerland.

The six companies forming the consortium were Riedl Architekten, an architectural group, Riget AG, which did the roof work, Elektro Künz, electric installer, Sauter Wärmetechnik GmbH, heating systems company, and Ernst Müller GmbH, the metalworks specialist.