Cornerstone CORNERSTONE_189_website_28 | Page 4

Cornerstone No. 189, page 4 Scots Kirk St. Andrew’s House Building New Roof Cover and Photovoltaic Panels The old roof cover was made of tin and has lasted more than 50 years. It had to be repaired many times because of leaks. It was at the end of its lifespan and could not be repaired anymore. The Session therefore decided to have it replaced. Thanks to our many donors and in particular to Oak Foundation for very generous grants, the project could be achieved. A tender document was prepared by M. Burgos and sent to three different firms in order to receive offers. The work was awarded to M. Burgos as his offer was the cheapest and also because of the renowned quality of his work. The existing insulation that was laid on top of the concrete roof slab (support- ing the roof) was improved by adding an extra layer of insulation that was blown onto the surface. It was quite a difficult job to carry out as the space between the roof and slab is very restricted. The removal of the old tin cover, the transport of the new one and of the solar panels was carried out with a mobile crane and also with a chain hoist. The wooden roof structure has been retained. The new cover is made of copper and should last for a very long time. The rainwater pipes and the gutters were also replaced by new copper ones. Many safety hooks were fixed onto the roof in order to protect the maintenance people. The opening to the roof was replaced by a slightly larger one, but access to the roof is still difficult. The tops of the ventilation ducts were sealed, as they had become loose and the chimney of the old refuse chute (no longer allowed) was demolished. Session decided to have solar panels installed as well. These are photovoltaic panels; there was however not enough space to also install a system that heats running water. As the roof is almost flat, the photovoltaic panels had to be fixed on top of the roof; another system called “integrated” would have replaced the roof cover. Offers were solicited from five different firms and the firm Electrosol was chosen. The 46 panels (make ALEO, monocrystalline) installed on the roof produce 300W each, that means a total of 13.8 Kw. According to Electrosol the estimated annual production will be about 13'400 Kwh. The panels produce direct current that is directed to the ground floor by way of a cable going through the old refuse chute and then to the roof of the basement and towards the inverter. The inverter transforms direct current into alternative current and is installed opposite the electricity switchboard. The electrician has installed a new electricity meter that reads the consumption of the whole building. The electricity produced is used primarily by the building's users and the surplus is sold to the at a reduced