Welcome to NZGBC's Energy and Carbon Calculator for Homes.
A tool for calculating a home's thermal comfort, energy and carbon emissions.
The software may be used for testing designs against the Homestar energy and carbon requirements.
There is also the facility to test results using the modelling methodology in NZS4218 as referenced by the New Zealand Building Code.
Please contact NZGBC to obtain an ECCHO license. Once purchased, your email address will be set up in ECCHO and then you can register your username and password below.
Please register or login to use ECCHO.
Brief Instructions
Please enter dwelling data in the following sequence:
Projects/dwellings
A project can be a single house, a collection of houses (or apartments) or a collection of design variations you wish to test.
Begin a new project on this page and define dwellings within that project.
Use this page to set which current project you are working on. The actual dwelling being worked on can be changed at any time in the top navigation bar. This is useful if you want to compare specifications or results between dwellings.
Start new project
Assemblies
Define the types of walls, roofs and floors used in your projects. Assemblies are unique to each project, but may be copied from other projects here as well.
Note: Change the display from R-values to U-values from the navigation menu.
Areas
Define the different areas of walls, roofs and floors in the current dwelling you're working on.
Thermal bridges
Define the dwelling's thermal bridges.
Windows
Define the dwelling's windows.
Ventilation
Define the dwelling's ventilation system.
Systems
Define the dwelling's space heating, hot water and lighting systems. If you wish you can also calculate energy consumption from appliances.
Results
See the calculated energy use and carbon emissions for each home in the project.
Change Log
The calculation engine in ECCHO is subject to an NZGBC Expert Reference Panel. See NZGBC website for current panel members.
NZGBC reserves the right to periodically amend the calculation algorithms following expert advice and recommendations. The following change log sets out changes that have been made since the inception of ECCHO.
The calculation version used by a project is set to the latest version when a project is created. All subsequent dwellings created in that project will use that calculation verison. Any projects copied using the copy function will also copy the original calculation version.
To use the latest calculation version for existing dwellings, create a new project and then copy dwellings into it.
| Calculation Version | Changes |
|---|---|
| v1 | Inception |
| v2 |
Bug fix. In v1 cooling demand and overheating were calculated using the winter ventilation rate (i.e. the greater of 0.35 ach and 7.5 l/s/p). Corrected to use the user-defined summer bypass rate. |
| v3 |
Bug fix. Custom internal heat gain now calculated using custom occupancy (set in Systems/Appliances and Renewables) rather than standard occupancy. This is used for calculation of cooling demand and overheating in both Homestar and Custom calculations. Ignored for winter heating demand in Homestar and H1 calcs. |
| v3 - addendum |
No change to main calculation methodology. But projects registered after 27 August 2024 have revised occupancy calculation. See Homestar Technical Manual appendix B. |
| v4 |
Climate data updated to latest NIWA set in line with 6th Edition building code. See weather files for Aotearoa New Zealand. |