Architectural Energy Efficiency

This is an architecturally-designed 2-storey holiday home built in 2009, a contemporary timber and corrugated steel construction on a large exposed coastal block. The home is well-designed and well-built for energy efficiency including double glazing, insulation throughout the ceiling, under the floors and in the walls.

The owners’ interest is to ensure the house is optimally energy-efficient prior to a planned installation of solar and conversion to greater electrification. Both the tank water and septic systems operate with electric pumps making power reliability/resilience important considerations.

Some of the main observations by the assessor included the presence of a large number of old-style downlights that are inefficient and compromise the ceiling insulation.

Also, the instantaneous bottled gas Hot Water System pipes hot water significant distances across the house, consuming eight large cylinders per annum. The open fire (together with high ceilings) is not an optimally efficient or effective source of heating and requires supplementary heating via panel and oil heaters in some rooms.

While the inspection revealed good quality R5 polyester insulation in the ceiling and walls, thermal imaging showed some gaps and shifts in the wall insulation. The floor is well insulated.


Some of the more straightforward recommendations were to replace downlights with IC rated sealed LED units and adding a layer of 3R insulation in the entire ceiling including the bulkhead and across the new LED lights. The assessor explained that 10% gaps in insulation in the ceiling area reduce R3.5 rating to R1.)

Because double glazing needs to work in conjunction with good quality window coverings that provide a thermal blanket, the assessor recommended installing cellular top-up bottom-down blinds (Nordic, Luxaflex, or, the most cost effective option, Veneta.) Also, the owners could replace the existing shower heads with slow-flow shower heads (Methven Kirri Satinjet slow flow, available at Pure Electric at save both water and the cost of water heating.

An electric heat-pump (or two) should replace the existing gas Hot Water System which is both expensive and environmentally problematic. The assessor recommended 'Reclaim Energy', 'Sanden' or 'Therman' by Reece and also recommended a plumber with specific expertise.

Solar opportunities:

The installation of a solar system to help electrify the house was supported and inclusion of battery storage was recommended to provide power resilience in the face of outages. Solar would economically power 2xHWS heat pumps as well as a multi-head split system that would provide efficient, cost effective and environmentally-better heating to the whole house.

Prior to investigating solar, the assessor suggested that the owners arrange for a professional assessment of the limitations created by trees shading the north side of the home and the distance between the main power box and the house which could cause voltage fluctuations.

This modern home has a variety of different roof areas and angles which make it a good candidate for an effective solar installation

This home has a large number of ceiling penetrations (nine in this one photo) from down lights, fans and exhausts. These penetrations reduce the efficiency of the ceiling insulation, cause drafts and increase heating costs. Possible solutions include sealed downlights, exhausts with draft-stoppers and added ceiling insulation

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