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' Aims
The owners’ interest is to ensure the house is optimally energy-efficient prior to a planned installation of a solar system and conversion to greater electrification. Both the water tank and septic systems operate with electric pumps making power reliability/resilience also very important considerations.
The Assessor's Findings
Some of the assessor's main observations by included the presence of a large number of old-style ceiling down lights throughout the house. These were seen as both inefficient and a source of drafts because of the numerous ceiling penetrations and they compromised the ceiling insulation. The absence of internal blinds on the double glazed windows meant the windows could not provide a 'thermal blanket' to keep heat in winter and the cool in during summer.
The instantaneous bottled gas hot water system provides another opportunity for efficiency gains. There was likely significant heat loss as the hot water travelled through a network of under-floor hot water pipes over significant distances under the house to the key outlets in the house. This system was consuming eight large (45kg) cylinders of gas per annum.
The open fire (together with high ceilings) was also not an optimally efficient or effective source of heating. A number of the bedrooms also required supplementary heating via expensive-to-run electric panel and oil heaters.
The assessor's inspection revealed the sub-flooring is well insulated. While there was also good quality R5 polyester insulation in the ceiling and walls, thermal imaging showed some gaps and shifts in the wall insulation.
The potential for a solar system was very positive. The roof areas were large and had multiple well exposed north faces.
The Assessor's Recommendations
Some of the more straight-forward less-costly recommendations were to replace the old downlights with IC rated sealed LED units and to add 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 to save both water and the cost of water heating.
The assessor recommended replacing the existing gas hotwater system - which is both costly to run and environmentally problematic - with perhaps two smaller electric heat-pump Hot Water Systems located to serve different zones of the house.
The assessor recommended 'Reclaim Energy', 'Sanden' or 'Therman' to be installed by a plumber with specific expertise. The installation of a solar system to help electrify the house was strongly supported and inclusion of battery storage was recommended to provide power resilience in the face of outages. Solar would economically power the 2x Hot Water System heat pumps as well as a multi-head split AC 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.
Comments