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Home > Example Homes > Laba Residence - Dunedin Eco Home - Solar, wind etc

Laba Residence - Dunedin Eco Home - Solar, wind etc

Home Details

Year built
0 bedroom(s), 0 bathroom(s)
A residential dwelling located at Mission Cove, Company Bay on the Otago Peninsula was designed as a solar passive energy conserving home for Mike and Edith Laba. The design process began in May 2004. The principal requirement was for the dwelling to be energy efficient, environmentally friendly and built from sustainable resources. Consideration was also given to the coastal setting and natural landforms, reflecting the link between the natural and built environments. The construction began in December 2004, with the owners taking possession in November 2005. The house was fully commissioned, with all of its alternative energy plant and landscaping by April 2007.

Designed by EcoWorkshop Ltd

The cue for the design was taken from American architect Frank Lloyd Wright’s hemicycle houses. These were based around his concepts of “Organic Architecture.”

The house is a segmented arc of 72 degrees. The front arc has a radius of 19.9m and the rear arc of the house 28.5m from the centre north point.
Designed to make full use of the sun’s natural thermal heating abilities, the house has a 200mm concrete ground floor slab that acts not only as the key structural member, but also as a solar passive heat sink.

The exterior walls are precast concrete panels (Thermomass) constructed with 150mm of concrete on the internal face, 50mm of high density polystyrene as insulation with a further 100mm of concrete to the external face. This sandwiched concrete panel achieves a R5 insulation value. The structure has been designed in such a way that a complete thermal break has been achieved between ground and dwelling.

Care was taken in the design process to ensure that the materials were environmentally friendly plus toxin free whilst still complying with the requirements of the Building Act (2004). All exterior joinery is thermally broken, double glazed, filled with argon gas and Low E film applied to achieve a high standard of heat retention.

The house was designed to make full use of the sun’s natural thermal heating abilities and to use the best insulation available at the time of construction. Careful consideration was given to selecting a section/lot that faced due north.

Starting with the floor which is a 200mm thick insulated concrete slab that acts not only as the key structural member, it also is a key element of the passive solar heat sink. The exterior walls are precast concrete panels called “Thermomass”. These consist of 150mm of reinforced concrete on the internal face then 50mm of high-density extruded polystyrene as insulation between a further 100mm of reinforced concrete on the external face. This 3 piece sandwiched concrete panel achieves an R5 insulation value. Design is in such a way that a complete thermal break has been achieved between outside and inside walls. This design gives a warm house in the winter and a cool house on a hot summer day. The inside temperature range has a small differential all year round. This makes for a healthier house also. The 300 mm thick external walls combined with the 200 mm floor gives a very sturdy structure against earthquakes and very strong south-westerly winds. The area experiences gusts of up to 35 m/s (126 km/h).

All exterior aluminium joinery “nulook – Millennium Suite” is thermally broken, (no heat transfer between outside and inside aluminium) double glazed, filled with argon gas and a Low E film applied to achieve a high standard of heat retention. Ceiling/roof space has polyester “poly+” insulation with an R3.2 value and “Air-Cell” (R2.7) between the roofing iron and roof support beams instead of the standard building paper.

On the north face of the house are the PV’s & hot water solar panels. The 16 “Uni-Solar – US-42” electric (672 w) and 1 hot water “Apricus - AP-20” (20 tube) panels are inclined to maximize output between winter and summer sun angles, approx. 450. Integrating the solar panels into the house design and keeping them low had two advantages - easy cleaning and less wind loading than if mounted on the roof.

The solar hot water collector comes with an indoor controller “Resol – Delta Sol B” with display and a variable speed pump. As hot water storage a 220-litre “Combo” stainless steel storage tank with a wetback option is installed. Storage tank built-in insulation is polyurethane 50mm thick.
Most of the hot water is derived from the solar panels with backup when needed from the gas (LPG) boiler “Ariston - Ecosystem”. This is also used to heat the house floor zones if the temperature drops below the perceived comfort levels. These are operated via a Room unit “Honeywell - Smartfit” controller. With this sophisticated controller one can set temperatures in the storage tank and in the main living area, offering up to three on and off times per day. It also recognizes weekdays and weekends.
Heating the bathroom and/or kitchen/living rooms (floor zones) are water pipes embedded in the concrete floor. The owners had to use this under-floor heating system last year (2006) only 15 separate days for about 4hrs each time to maintain the comfort zone. Two gas storage bottles (45lts each) are stored outside and replaced as required. The Gas boiler is housed in the garage and two well insulated special water pipes (flow & return) run from the garage underground to the house valve/control system.

Mains power for the house can be from the National Grid or from the battery supply. If the sun and wind have been unavailable for a few days the owners have the option of switching over to Grid power. This convenience comes at a small extra cost. Without this option the system would need a petrol/diesel generator to charge the batteries. The power company offered a reduction in line charges because the home is considered a “low user” but all used power is charged out at a slightly higher rate. Average monthly electric power bill is about $25 and the LPG gas is averaging at about $60 per month.

Both charges will be significantly less this year (2007) because the solar panels (PV & hot water) plus the wind turbines came on stream about May last year.
Having a “Centameter” instrument gives a wattage or current read-out of what power the house is using. The owners are constantly checking through the instrumentation for the available energy stored and the amount being used. Certain activities which require high energy input (vacuuming etc) are done when the energy being generated in the system is high.

The dishwasher “Miele - G2830 SCi” and washing machine “Miele - W 2653 WPS” have a unique program allowing them to use the systems own hot water instead of heating the cold water with electric power. Cooking is with gas on a 4-burner hob “Bosch – PCH 615FAU” and a gas oven “Parmco”. The kitchen also has a small half size electric oven “Parmco” used only when on grid power. For cold storage the kitchen has a low energy fridge/freezer “Gram – KF320 ”.The microwave oven is a “Bosch – HMT 9656AU” it can be used sparingly depending on battery State Of Charge, the same goes for the Vacuum cleaner “Nilfisk – X100”.

Lighting is a combination of LEDs and two types of compact fluorescents. In the bedrooms standard compact fluorescent lamps were used, and in the living/kitchen area and study room installed were “Megaman”, a compact reflector type (GU10). Rated power consumption of these lamps are 11 watts with an equivalent light output to a 50-watt standard lamp. These lamps boast a life of 15,000 hrs...

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