Capitalising On Solar Access Rights

Strata building roof tops are valuable real estate assets which have largely been untapped.  

The City of Sydney has funded a study of a complex in Glebe NSW to investigate viable alternatives for unused roof space to maximise returns for property owners.  You can download the case study and report from Wattblock.

Strata buildings can lease out their roof area for things like mobile transmission equipment.  However, this typically only uses perimeter space.  This study compares four different options for capitalising on unused roof space with analysis of returns per square meter.  The best returns came from a combination of solar energy for common power and heat pumps for common hot water systems.

​Besides reduced energy costs, these projects offer immediate benefits in terms of 'green building' valuation premiums of 10-14%, as previously covered in Strata Energy News. It was also considered that installing solar energy on the rooftop establishes solar access rights as a defence against possible future shading infringements.

The combination of solar energy and heat pump projects was estimated to cost $90,000 for a 200 square meter rooftop. Other benefits aside, a rapid 6.4 year payback is achieved through a 26% reduction in common area electricity costs and a 70% reduction in gas hot water costs. Furthermore, the heat pump component could be configured to run off solar power, thereby further contributing free hot water for residents during the day.
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Un-used roof space on Glebe strata building ... Ideal for Solar Energy and Heat Pump combination

​Options considered in the paper included:

Solar Energy for Common Areas. Using half the available roof area for a 10kW solar panel installation for common area power only. The project was estimated to cost $16,000 and to deliver a $2,700 annual energy cost savings giving a 5.6 year payback.

Community Solar Energy for Apartments. Using all available roof space a 20kW solar panel installation with 'digital solar' solution to make excess energy available for apartments. Project cost was estimated at $42,000 with payback at over 25 years due to high bill management fees for apartments.  Some alternative variations were explored.

Solar Thermal for Common Hot Water. Installation of solar collectors costing $53,500 and delivering a payback of 9.1 years.  The solar collectors use evacuated tubes to heat water via solar radiation and would take up one quarter of the rooftop.

Heat Pump for Common Hot Water.  Project costs of $74,000 were the highest of the options explored.  However, this project used the least amount of roof space at 17 square meters, and would deliver $14,000 in annual benefits giving a 6.6 year payback.

The various options considered have their pros and cons.  However, overall the study demonstrates that returns on rooftop assets are superior to most financial market returns without the same level of investment risks. Strata management companies are taking the opportunity to help strata customers better manage their assets.

Download the City of Sydney Case Study Overview and Report for more information. For further reading on community solar try Digital Solar and Strata.  The report is also covered in Fifth Estate.

Ross McIntyre
Contributor, Strata Energy News​
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