When designing a new home, some simple upgrades can improve its performance. These go beyond the minimums required by the NZ Building Code and can help to:
- keep temperatures more comfortable for longer
- use fewer resources such as energy and water
- make it cheaper to run.
How to use
1. Confirm the budget with your client.
2. Determine the theme(s) you and your client want to address:
3. Pick the desired features with your client, up to the budget.
4. Develop an accurate quote.
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.)
|THERMAL improvement||extra cost||yearly savings||thermal benefit|
|Living areas facing north, garage facing south||Marginal||$120||Very good|
|R4.0 bulk ceiling insulation (upgraded from R2.9)||$390||$40||Good|
|R4.6 bulk ceiling insulation (upgraded from R2.9)||$1,300||$90||Good|
|Thermally broken aluminium-framed windows||$1,900||$190||Very good|
|Thermally broken, aluminium-framed, double glazing with low-E coating||$4,100||$410||Excellent|
|Insulated concrete slab|
|50 mm expanded S-grade polystyrene insulation, continuous, under entire slab (i.e. not pod-style)||$2,300||$310||Very good|
|As above, but with 20 mm polystyrene around perimeter ||$3,600||$360||Very good|
|50 mm expanded polystyrene insulation under slab + exposed slab in living areas||$3,100||$300||Very good|
|As above, but with 20 mm insulation around perimeter||$4,400||$360||Excellent|
|50 mm expanded polystyrene insulation under slab + R2.8 walls + R4 ceiling + low-E glazing||$6,300||$430||Excellent|
|As above, but with thermally broken frames as well ||$8,600||$800||Outstanding|
The extra cost refers to the costs over and above what a more standard component or system would typically cost to purchase initially. 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.
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.)
|ENERGY improvement||extra cost||yearly savings|
|Photovoltaic-ready house (installing cabling only)||$400||NA||NA|
|3 kWh grid-connected photovoltaic system fully installed||$10,000||(see note 1)||(see note 1)|
|Appliances and lighting|
|4 Energy Star fridge-freezer (380 litres)||$100||$60||Good|
|Correctly sized heat pump||$0||$150||Very good|
|All lighting energy efficient (CFL or LED)||$300||$150||Very good|
1. Savings are difficult to determine given the rapid photovoltaic (PV) price changes and a number of other factors. See the Photovoltaic (PV) Design fact sheet for more information.
The extra cost refers to the costs over and above what a more standard component or system would typically cost to purchase initially. The yearly savings is the estimated benefit in lowered energy costs resulting from better appliance efficiencies.
The following improvements will help to manage water resources better. As Wellington's supply and waste water council charges are based on capital value, the suggested improvements below are based on the most cost-effective solutions from usage-based charging councils.
|WATER improvement||extra cost||yearly savings|
|Small fittings and appliances|
|4 star or better WELS2 toilets ||Marginal||1,600 litres||Good|
|4 star WELS kitchen + bathroom tapware ||Marginal||2,300 litres||Good|
|4 star or better showerheads ||Marginal||57,100 litres||Excellent|
|Rainwater tank systems|
|1,000 litre water tank with feed pump to garden||$2,400||93,000 litres||Outstanding|
|25,000 litre water tank with feed pump to whole house3||$7,400||138,000 litres||Outstanding|
2. WELS = Water Efficiency Labelling Scheme.
3. Check regulations with local council first.
The extra cost refers to the costs over and above what a more standard component or system would typically cost. The yearly savings is the estimated benefit in terms of saved water over a typical year given typical occupants.
The performance upgrades are based on independent research by BRANZ and are region specific where possible. Only the most cost-effective improvements have been selected, based on homes consented in 2012. The cost and benefit figures are averages derived from actual consented plans and take inflation and returns into account. All figures are estimates and should be seen as starting points for discussions.
Once the upgrades have been chosen, the estimated figures for extra costs will need to be more accurately determined and will vary depending on the specific design.
If you would like the detail on how this was calculated, including the full (unfiltered) list of improvement upgrades considered, see the background document Up-Spec: Background Research
The figures in the regional checklists consider those costs and benefits that are reasonably easy to quantify. Harder to quantify - but that might be even more important - are the:
- health and comfort benefits from having a warmer, drier home
- improved resilience and self-sufficiency for the home
- Homestar points resulting from the upgrades.
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