Viridian Solar has developed Cirrus, a solar heating system suitable for installing in tall residential blocks
One of the challenges of installing solar water heating systems in tall buildings is that linking dedicated panels to each flat can result in an enormous volume of extra pipework, resulting in lower apartments suffering disproportionate heat losses from the long runs of pipe. A communal heating system that distributes hot water to every apartment from a central hot water tank, on the other hand, requires a plant room and heat metering for billing.
The Cirrus system links an array of solar panels together with a pair of pipes that enter the building and circulate the heat around. A special control unit in each apartment then determines when heat can be added to the hot water cylinder in each apartment. The unit monitors the temperature of the flow in the solar loop, and only opens a valve to allow heat to flow into the solar heating coil in the hot water cylinder when the temperature in the loop is sufficiently high to add heat. The energy savings are optimised compared with individual solar systems owing to “load sharing” – for example, if the residents of one flat are on holiday, the other residents use their allocation of solar panel area.
One of the first projects to benefit from Cirrus was Northpoint, a six-storey development of 47 residential flats in Islington, north London, by Inspace Homes. A renewable energy target of 10% was met with a communal array of Clearline solar water heating panels on the roof, linked to a Cirrus communal heating system.