New Zealand's First Eco-Rated 10 Star Home - PDL by Schneider Electric | ArchiPro

New Zealand's First Eco-Rated 10 Star Home

A Christchurch home has received New Zealand’s first-ever 10-star Homestar rating, an award that recognises its energy-neutral, sustainable footprint. Schneider Electric designed its innovative electrical infrastructure, enabling the home to switch seamlessly between mains and solar power.

The 140m2, two-storey home was designed by Christchurch architectural designer Bob Burnett, a leading advocate of sustainable homes. Its thermally-efficient design includes solar walls that pre-heat ventilation air through an energy recovery ventilation system, a dual heat hot water and hydronic underfloor heating system and fully-insulated foundations and slab-edges (to reduce heat dissipating from concrete floor slabs).

Complementing these are numerous eco-friendly features: rainwater harvesting, reusable greywater, water-efficient fittings, solar power and energy-efficient lighting and electrics. The reduced use of heating and electricity should keep the home energy-neutral, leaving it free of power bills.

The 10-star rating was awarded by Homestar, a system run by New Zealand’s Green Building Council. It uses a 1-10 scale to measure factors such as energy and water use, waste, materials, ventilation and health and comfort. Homes built to New Zealand’s current building codes typically rate three on Homestar’s scale.

Bob says thermal and energy efficiency in New Zealand homes lags far behind the rest of the world, and he plans to change that. “Energy-efficiency doesn’t have to be costly. As this home illustrates, it’s actually about using existing technology in a cleverer way – simple but smart.”

The Electrical Solution

The home’s electrical supply is split between conventional 240 volt AC from the grid and a 24-volt DC system from 18 roof-mounted solar panels. Evening off the demand is met by the batteries – the home automatically switches to 240 volt mains when the batteries run low. The overall configuration demanded a relatively simple electrical design, but it came with a caveat.

To meet the architect’s energy-efficient, sustainability brief, says Schneider Electric’s Dave Chapman (Channel Manager – Residential), “we had to think a little differently. Considering that the home is designed for a family, affordability was key. Energy-efficient technology often carries a cost premium. Bob wanted a solution using standard, off-the-shelf technology.”

Dave’s team opted for energy-saving techniques such as motion detectors – sensors that switch off lights if no one in the room, and to support that they enhanced conventional wiring templates.

“For example, we introduced a sunset switch to specific circuits. It automatically renders these circuits active or inactive depending on whether its day or night. By ensuring that specific lighting circuits can’t be used, any chance of accidental wastage is eliminated.”

The home is equipped with Schneider Electric’s Saturn Zen range of switches. “Again, while this is one of our standard models, we’ve wired the switches in an unconventional way. Using a relay in the switchboard, we’ve created an “all-off” functionality. The home’s entire lighting system can be shut down from one switch, again eliminating any possibility of lights being left on.”

To help the home owner keep track of electricity consumption and solar power availability, an Eco-mind energy monitor has been installed. It gives owners an easy-to-read-and-understand tool for managing and modifying their energy use patterns.

Because mobile technology has become so prevalent in the modern lifestyle, the home has been equipped with multiple USB charging ports to service devices such as phones and tablets. With a five-star rating the USB chargers are particularly energy-efficient.

While the technology we’ve installed doesn’t meet the conventional definition of home automation, says Dave, “in effect the design and the way it’s been configured delivers a similar outcome.”


The home’s solar component was supplied by one of Schneider Electric’s specialist partner companies in Christchurch, Canterbury Power Solutions (CPS).

The system’s 18 photo-voltaic panels are each rated at 260 watts and charge two sodium-ion, 24-volt batteries housed within a wardrobe. “The panels’ combined output of 4.16 kW,” says CPS owner Murray Marquet, “is easily sufficient for servicing the two batteries. These are maintenance-free and fairly compact – each battery measures 300 by 300 by 90 millimetres (LWH).”

The DC power is converted to 240 volt AC by a Schneider Electric inverter connected to a Battery Management System (BMS). When the BMS senses that battery power is too low, it switches back to the national grid supply. It does this with the help of a simple DIN rail device mounted in the home’s switchboard.

“The switchover is automatic and seamless,” says Murray. “And as a grid-tied system, the solar configuration also feeds electricity back on to the national grid when there is excess battery power. It’s clean electricity delivered to the grid at the standard 50Hz frequency. There are no rogue wave-forms.”

Homes with improved energy and thermal performance are likely to become much more common if Bob has anything to do with it. He has been instrumental in establishing the SUPERHOME movement – a nationwide industry initiative to normalise energy efficient, better quality homes.

SUPERHOME movement aims to build 1,000 homes with a six or higher Homestar rating. A recent Auckland study, he points out, shows that a six-star home only costs about 2.2% more to build than the standard New Zealand three-star home, and that a six-star rating will halve a home’s energy bill.                                                

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