A number of New Zealand-focused energy performance and design tools are available to help you design energy efficient buildings and assess their performance.

ALF3

ALF (Annual Loss Factor) software provides a step-by-step method of calculating the energy performance of conventional New Zealand homes. It is an alternative solution for determining the Building Performance Index (BPI) which can be used to show compliance with NZ Building Code Clause H1 Energy Efficiency. The software also calculates compliance with the Schedule and the Calculation Methods of NZS 4218:1996.

ALF3 is available in either hard copy or digital format.

Carbon calculators/tools

BRANZ’s Easy Guide to Being a Climate-Friendly Kiwi (PDF, 1.2MB) provides easy-to-use, practical information on how, as small business owner/manager, an individual or employee you can reduce your greenhouse gas emissions on a day-to-day basis.

The CarboNZero programme, administered by Landcare Research Ltd, provides tools for businesses and individuals to calculate, reduce and offset their greenhouse gas (GHG) emissions.

The World Resources Institute’s safeclimate website has a carbon footprint calculator.

Window Efficiency Rating System (WERS)

The design and installation of windows has a major impact on a building's energy efficiency with up to 40% of heat loss being through glass. Windows affect how much energy buildings use, how warm or cold they are and how comfortable they are for the occupants.

The Window Efficiency Rating Scheme (WERS) is the official, independent rating system used by the New Zealand window industry to assess and rate the performance of external glass doors and windows.

The system shows the performance of glass and frame types in terms of heating, cooling, condensation and fading, with each area being given a star rating from one to five – the higher the rating, the better the energy performance.

Frames considered include aluminium, thermally broken aluminium, composite timber and aluminium, timber and PVC. Glazing includes clear glass, tinted glass, laminated glass, double glazing options and Low-E double glazing.

How it works

The star rating is based on an average house with 20 external doors and windows. It gives bands of performance for each of the three climatic zones within New Zealand to allow you to evaluate the cost and benefit implications of various frame and glazing combinations.

(While specifying/installing the appropriate windows will provide significant benefits in comfort and reduced energy consumption, how the windows are installed is also important: construction gaps can be sources of heat loss and uncontrolled ventilation.)

 

For information, see the Window Association of NZ website or purchase BRANZ Bulletin 474 – WERS.