ROOFTOP PV
Quick facts:
–    SA’s direct solar radiation levels amongst top 3 in the world
–    More than 2 500 hours of sunshine/year
–    Prediction: rooftop PV likely to be between 3.5GW and 11.6GW by 2035

Drivers:
–    Rising electricity costs
–    Declining technology costs
–    Advances in energy storage systems
–    Needs little maintenance
–    Long-term performance guarantee

Installation:
–    Household: 2kWp to 10kWp
–    Commercial: 10kWp to 1MW
–    On North, East and West-facing rooftops
–    No shadows!

Cost:
R0.80 to R1.20/kWh ≈ R20 000 and R30 000 for 2kWp that will provide ±10kWh/day, enough to power a small household

Sources: The State of Renewable Energy in South Africa 2015 report SAPVIA. Consolidated Power Projects Energy Solutions

REFLECTIVE ROOFS
Quick facts:
–    Solar radiation causes 99% of heat in our atmosphere
–    Reflective roofs mitigate the urban heat island effect
–    Roofs account for ± ¼ of surfaces in cities
–    They not only white, but come in a variety of “cool” colours

NB Considerations:
–    Solar Reflectance Index (SRI) = the amount of solar energy directly reflected
–    Thermal Emittance (TE) = the solar energy that is indirectly heating the atmosphere & adjacent spaces
–    Reflectivity values over time
–    The product warranty

Sources: Center for Environmental Innovation in Roofing Global Cities Cool Roofs and Cool Pavements Tool Kit

GREEN ROOFS
Types:
1.    Extensive, self-sustaining ecological roof, normally on sloping roofs with limited access
2.    Intensive = intricate & lush roof garden, normally on flat, accessible roofs

Benefits
–    Long-term sustainability
–    Better thermal & acoustic insulation
–    Energy efficiency
–    Help manage storm water
–    Absorbs CO2 and other pollutants
–    Attractive

4 things to consider:
–    The strength of the building structure
–    The roof slope
–    A building’s location & micro-climate on roof
–    Plant selection

Sources: Green Roof Designs www.greenroofs.com