AWPower engineers recently completed a sustainable living housing project in Harfield Village (Claremont) where, for large portions of the year, there is very little to no reliance on the electricity grid and municipal water supply.
Below is our story, with indication of approximate expenditure.
Firstly, we reduced the load. The 100 year old cottage in Durham Street was almost totally rebuilt and enlarged. Major interventions to reduce the electricity and water load was achieved by installing LED lights, fitting LED lights with day/night sensors for outside lighting, installing sky lights in the roof, paving outside areas with dedicated but limited area for plants, supported by an automatic irrigation system fed from a greywater system. The sky lights were constructed from modern roof sheeting that allows for light to enter but keeping heat out. Sky lights were fitted over the kitchen work area, bathrooms and corridors where the typical household would switch on the lights for better vision during day-time. A conventional geyser was fitted with factory applied temperature insulation, with element size reduced from typical 3kW to 2kW to reduce peak electricity load.
Typical costs: 5W LED downlights R39 each; geyser element R179; PolyCarb Roof Sheeting R90 per metre.
Rainwater harvesting. AWPower engineer Warren Versfeld designed a fully integrated rainwater harvesting solution that supplies the entire cottage with drinkable (potable) water. The system consists of 3 x 1,000L Slimline water tanks that are fed from multiple gutters collecting from most of the roof area. From the tanks the water is pumped with an 850W variable speed motor through a 3-stage particle filter system with a UV-filter that would ensure the water is purified.
The energy efficient variable speed drive (VSD) pump has the functionality to gradually increase its power draw, to maintain the pressure set for the system, rather than being a conventional 850W pump with constant 850W power draw. The system includes, as backup, a municipal supply into the tanks with a ball valve that will collect municipal water should the rainwater tanks run low. Provision is made for expanding the water tank capacity, for example an underground tank of 6,000L can be added to the existing system.
Typical costs of rainwater harvesting solutions (including piping, installation & VAT):
- Rainwater harvesting with 5,000L tank, first-flush filter, gravity feed to garden/pool R14,000
- Rainwater harvesting as above + VSD pump to supply garden/toilets (non-potable) R28,000
- Integrated rainwater harvesting with VSD pump & filter system (drinkable water) R46,000
Automated Greywater solution. A 120L greywater system that is fed from the cottage’s bathrooms were installed, driving an irrigation system that will engage when the 120L tank is full, providing an automated solution. This system ensures that not a single drop of water from the bathroom basins, showers and bath is wasted.
Typical cost of greywater tank with pump, installation and irrigation system R17,000.
Solar PV system. Warren also design & managed the installation of a 6kW Off-Grid heavy-duty Inverter, together with 4kWp of rooftop mounted PV modules that stores up to 10kWh of generated electricity into a lead-acid battery bank. The system is suitable for supporting the full load of the cottage including the conventional geyser which is fitted with a 2kW element, managed by a Geyserwise controller. The inverter has the functionality to automatically connect to the grid when running out of PV or battery power.
Typical costs of solar PV system including installation R169,000
A smaller system with 3kWp solar PV and 6kW inverter would cost in the region of R130,000
You are invited to view AWPower’s Sustainable Living Cottage
|Where:||9 Durham Street, Harfield Village, Claremont|
|When:||Friday 8 and Sunday 10 Sep 2017
Opening hours 11:00 – 17:00
Please RSVP firstname.lastname@example.org.
|Off-Grid Solar PV Solution|
|Inverted Power Driving Conventional Geyser|
|Pressurized Rainwater Harvesting Solution|
|Grey Water Solution|
|Energy Efficient Lighting|
|Intelligent Management System|