Twenty years on from HEEP, BRANZ is answering the call from stakeholders to provide an updated picture of home energy use and housing conditions in Aotearoa New Zealand.
HEEP2 data will help to guide targeted initiatives and policies to improve housing outcomes and energy wellbeing.
The data will inform innovative solutions to improve energy efficiency and reduce greenhouse gas emissions.
Watch HEEP2 Overview video
Download HEEP2 Overview handout
Download the Full Household Survey
Download the Data collection catalogue
Accessing the data for public-good research
The long-term goal is for anonymised subsets of HEEP2 data to be available via Stats NZ Integrated Data Infrastructure (IDI).
Household samples
National sample
HEEP2 is collecting data, at varying levels, on over 750 homes spread across all regions of Aotearoa New Zealand. They were recruited from a pool of over 2,800 respondents from Stats NZ Tatauranga Aotearoa's Household Economic Survey.
Canterbury-based high-performance and code-minimum sample
A parallel, Canterbury-based study has recruited an additional 40 households to compare new builds (code-minimum) and higher-performance homes.
The homes in the higher-performance group were built to standards such as New Zealand Green Building Council (NZGBC) Homestar 7 or above, Passive House or Superhome.
The code-minimum homes were recruited via a follow-up to BRANZ’s New Home Owners’ Satisfaction Survey.
This study received co-funding from MBIE and the NZGBC.
Different levels of data collection
Households have been recruited to HEEP2 sample groups, which have varying levels of data collection:
- Light: short self-completion household survey including consent for access to energy use data from their retailer(s) (333 households)
- Medium: as Light plus an in-home interview and building and appliance surveys, to collect more detailed information on the household occupants, their energy use attitudes and practices, the construction of the home and household energy using or generating appliances (138 households)
- Full and High-performance and code-minimum: as Medium plus at least 12 months of detailed in-home monitoring (described below) and a final exit survey (287 households in the Full nationwide sample; 43 households in the Canterbury-based high-performance/code-minimum study).
The HEEP2 national study includes a nested sample of households taking part with varying levels of data collection, all recruited via the Stats NZ HES.
Detailed in-home monitoring data
The monitoring data collected for the Full and 'High-performance/code-minimum' samples includes:
- Mean power (W) per minute for up to 14 electricity circuits within the home, including the overall main incoming/export circuit and separately controlled hot water circuit if present
- Temperature, CO2, relative humidity, atmospheric pressure and light intensity at 15-minute intervals in living areas, up to 3 bedrooms, as well as other spaces where monitoring was feasible
- Temperature and relative humidity in the immediate vicinity of specific heating and cooling appliances to detect usage
- Temperature at the cold inlet and hot outlet of hot water system (cylinder or instantaneous) to understand hot water draw off (together with shower flow rates measured as part of the building survey)
- Gas use for a small sample (around 30) of households with reticulated gas supplies, and who use gas for heating and/or hot water
- Temperature and relative humidity outside the house, complemented by similar data from the nearest NIWA weather station.
Project timeline
HEEP2 household recruitment took place from August 2021. Fieldwork started in August 2022 and continued until April 2024, with monitoring completed in April/May 2025 (12 months after equipment installation in the last house).
Last updated: 4 July 2025