You can also determine how to make improvements that will make your home more comfortable, healthier and cheaper to run.

Home performance

The Homestar online tool gives you much more than a rating. Once you have filled out all the questions, the tool will not only give you an indicative star rating for your home’s performance, it will generate recommendations for improving your home. You can then prioritise these according to cost or outcome.

Carbon Dioxide Calculators

The CarboNZero Household Calculator is an online tool designed to estimate household carbon dioxide emissions.

By selecting which appliances, transport and home energy type your household uses, you can calculate how much carbon dioxide your home uses. You can also use the calculator to figure out how much impact different appliance/transport/energy use options would have on your home's carbon dioxide emissions.

The CarboNZero Household Calculator was developed by Landcare Research. You can access the tool from CarboNZero website.

Energy use

The Energywise website has a series of calculators and tools:

Running Costs Calculator – this helps you select appliances by showing you how the star rating affects the amount of energy used, and how much the appliance will cost each year to run.

Heater Sizing Calculator – this tool helps you work out exactly what size heater you need.

Building and Renovating Tool - this step-by-step tool should give you an indication of the things to think about when building or renovating, but you should consult a professional for detailed and specific advice.

Home Energy Efficiency Tool - this step-by-step tool can help you identify the opportunities for energy savings in different areas of your home.

Electricity savings

Find out how much you can save by switching electricity retailers on the Powerswitch website’s Savings Calculator.

Lighting

The RightLight website helps you make smarter lighting choices for your home:

Bulb Finder – this helps you decide what to replace your inefficient bulbs with

Bulb Savings Calculator – shows you how much you’ll save with an energy-efficient light bulb

Household Savings Calculator – shows you how much you’ll save if you replace all your inefficient light bulbs
Carbon footprint calculator.

Carbon footprint calculator

The CarboNZero Household Calculator is an online tool designed to estimate household greenhouse gas emissions.
By selecting which appliances, transport and home energy type your household uses, you can calculate how much greenhouse gas emissions your home generates. You can also use the calculator to figure out how much impact different appliance/transport/energy use options would have on your home’s greenhouse gas emissions.

The CarboNZero Household Calculator was developed by Landcare Research. You can access the tool from CarboNZero website.

Insulation calculators 

The Design Navigator website provides online tools for assessing R values for roofs, walls, floors and retaining walls, and whether buildings will meet the H1 requirements of the Building Code.

Design tools

Google Sketchup is a software package for creating three-dimensional images of homes and buildings (or any other object). It can be useful for visualising the impact of a building on a site or visualising the amount of shade that might be cast by buildings, trees etc. You can download a free version from the Google Sketchup website.

Building costs

The Ministry of Business, Innvoation and Employment, Building and Housing information website has a Quick Building Costs Calculator that will give you an idea of how much your particular project will cost.

Wall and roof claddings

The life-cycle analysis of wall claddings tool, developed by BRANZ Ltd, provides data on environmental impacts of common wall claddings used in New Zealand homes.

The initial and life-cycle costs of the claddings are also provided. The tool enables the environmental impacts to be combined with the cost data to arrive at an overall 'score' for each cladding. The intended audience is designers and environmentally aware building owners. 

A similar tool has been developed for roof claddings.

The tool can be downloaded from the Wall and roof cladding analysis tool page of BRANZ Ltd's website.

Other overseas tools/calculators

There are many other online sustainable building calculators and tools available internationally. While these may offer guidance on sustainable building, they will not necessarily be applicable in New Zealand conditions. See the websites of Australian sustainable building tools BASIX and NABERS, or, for a list of other internationally available tools, the energy calculators and software page of the US Department of Energy's energy efficiency and renewable energy website.

Note: the fact that this website links to other sites does not imply endorsement of any information or views expressed on them. See About Smarter Homes for more information about our policy on linking to external sites.