Cirrus - solar water heating for high rise buildings, flats and apartments

Solar heating for taller buildings

When implementing solar water heating systems for apartment blocks or larger buildings, Viridian Solar offers a number of options, including Cirrus a unique distributed communal system with many advantages for developers of high rise buildings. The most appropriate system will depend upon the design and use of the building:
Individual Solar Systems Each individual apartment has its own hot water cylinder and its own solar panel or panels. Dedicated flow and return pipes link cylinder to panel, and pumps and controls are in each apartment. However, individual solar water heating systems start to reach a practical limit in multi-dwelling buildings once their height exceeds three storeys. Two pairs of insulated pipes linking dedicated solar panels on the roof to a hot water cylinder in each flat quickly add up to large service risers in taller buildings. Heat losses grow as pipe length increases, so lower floor flats see reduced energy benefits. Weather-tight penetrations need to be made to bring large numbers of pipes into the building.	It is possible to connect a dedicated solar panel to each individual flat, however the complexity quickly increases and heat losses are high for lower flats.

Communal Solar Systems

Another approach is to combine the solar panels together into a communal system, heating large solar buffer vessels in a plant room. Solar heated water passes to a second (smaller) hot water store which is heated by an auxilliary heater (e.g. gas, oil, biomass). Hot water ready for use is then circulated around the building, and drawn off in each apartment as required.

Combining solar panels into a communal system simplifies the installation, but space is needed
for a plant room and hot water needs to be metered.

Pipe runs are simplified compared to the previous option, with only two pairs of pipes running in the riser. A more efficient utilization of the solar panels is also possible, often reducing the overall cost of the solar installation.

However, there are disadvantages to this type of solar heating system in some situations.

The need for a plant room means giving up valuable habitable space, the centralised hot water needs to be distributed to the dwellings - either free of charge (with a risk of over-use) or requiring metering. Heat losses from the hot water circulation can be high.

This type of system is generally most suitable for buildings where a centralised heating system is acceptable such as Extracare, hotels and healthcare buildings. (See Case Study 003 here)

Cirrus

The Cirrus system from Viridian Solar combines the strengths of the two above approaches, while eliminating the drawbacks of each.

Solar panels are grouped into a shared array, often reducing the number needed to meet energy targets. Only two pipes enter the building into the service riser. The solar heat is circulated past each flat where a Cirrus Control Module decides when heat can be added to the hot water cylinder. Flow balancing components ensure that each apartment gets a fair share of the available heat.

On days when the solar does not achieve a high enough temperature in the cylinder, the heat is topped up by an individual boiler or immersion heater in each apartment.

Cirrus simplifies solar for tall buildings.

Further Information

How it Works - Introduction to Solar Water Heating

Pitched roof integrated solar panels

Solar panels for installation on flat roofs

Case Studies

Gallery

Recommended Downloads
	Aim Higher Cirrus Distributed Communal Solar System Brochure. (PDF 0.3MB)	Case Study 006 Inspace Homes, Northpoint Development of 47 flats. 10% renewable energy target achieved (PDF 1.0MB)