Summary of cost effective upgrades in Invercargill region [PDF, 251.1 KB]
The extra cost in each table refers to the costs over and above what a more standard component or system would typically cost to purchase initially.
Comfortable temperatures
The following improvements will help make the house more comfortable while needing less heating or cooling over the year, therefore saving on energy costs. (Note that an accurate yearly savings figure cannot be determined by adding two or more thermal improvements together.) The yearly savings are a result of the lower need for space conditioning energy use only. Figures are based on the needs of typical spec homes.
| Thermal improvement | Extra cost | Yearly savings | Thermal benefit |
|---|---|---|---|
| HOUSE ORIENTATION | |||
| Living areas facign north, garage facing south | Marginal | $200 | Very good |
| WINDOWS | |||
| Thermally broken aluminium-framed windows | $1,900 | $250 | |
| Thermally broken, aluminium framed, double glazing with low-E coating | $4,100 | $580 | Excellent |
| INSULATED CONCRETE SLAB | |||
| 50 mm expanded S-grade polystyrene insulation, continuous, under entire slab (i.e. not pod-style) | $2,500 | $490 | Excellent |
| As above, but with 20 mm polystyrene around perimeter | $3,900 | $580 | Excellent |
| COMBINATIONS | |||
| 50 mm expanded polystyrene insulation under slab + exposed slab in living areas | $3,200 | $310 | Excellent |
| As above, but with 20 mm insulation around perimeter | $3,900 | $580 | Excellent |
| 50 mm expanded polystyrene insulation under slab + R2.8 walls + R4 ceiling + low-E glazing | $6,300 | $980 | Outstanding |
| As above, but with thermally broken frames as well | $8,600 | $1,200 | Outstanding |
Energy efficiency
The following improvements will help make the house cheaper to run. (Individual improvements can be added together to provide combined extra costs and yearly savings.) The yearly savings is the estimated benefit in lowered energy costs resulting from better appliance efficiencies.
| Energy improvement | Extra cost | Yearly savings (per household) | Energy benefit |
|---|---|---|---|
| RENEWABLES | |||
| Photovoltaic-ready house (installing cabling only) | $400 | NA | NA |
| 3 kWh grid-connected photovoltaic system fully installed | $10,000 | Difficult to determine | Difficult to determine |
| APPLIANCES AND LIGHTING | |||
| 4 Energy Star fridge-freezer (380 litres) | $100 | $60 | Good |
| Correctly sized heat pump | $0 | $290 | Very good |
| All lighting energy efficient (CFL or LED) | $300 | $150 | Very good |
Water management
The following improvements will help to manage water resources better. As Invercargill's supply and wastewater council charges are fixed, the suggested improvements below are based on the most cost-effective solutions from usage-based charging councils. The yearly savings is the estimated benefit in terms of saved water over a typical year given typical occupants.
| Water improvement | Extra cost | Yearly savings (per household) | Water benefit |
|---|---|---|---|
| SMALL FITTINGS AND APPLIANCES | |||
| 4 star or better WELS toilets | Marginal | 1,600 litres | Good |
| 4 star WELS kitchen + bathroom tapware | Marginal | 2,300 litres | Good |
| 4 star or better showerheads | Marginal | 57,000 litres | Excellent |
| RAINWATER TANK SYSTEMS | |||
| 1,000 litre water tank with feed pump to garden | $2,400 | 80,000 litres | Outstanding |
Updated: 20 September 2023