Source
https://www.branz.co.nz/pubs/research-reports/sr452/ — original source (opens in a new tab; the file is not redistributed)
Summary
BRANZ Study Report SR452 (Plagmann, White & McDowall, 2021) measured the winter indoor climate — temperature and relative humidity — in 88 New Zealand homes and assessed mould growth in each. It found bedrooms that are cold (average 16.4°C, below the WHO 18°C minimum for the large majority of the night) and humid (relative humidity above 65% nearly half the time), conditions that drive the mould growth observed in many bedrooms and bathrooms. The study attributes this to a lack of heating and/or ventilation and links it to potential adverse health effects. For Neobiome Intelligence it is hard NZ evidence for the cold-damp-mould problem at the room scale, corroborating HEEP2’s bedroom temperatures, and an anchor for the healthy-housing design case.
Key claims
- claim: "SR452 (Plagmann, White & McDowall, 2021) measured temperature and relative humidity during winter in 88 homes across New Zealand (including Auckland, Wellington and other locations) and determined a mould index for each home."
source_location: "Abstract (p.ii); §Methods"
- claim: "The average temperature inside bedrooms was 16.4°C, and bedrooms were below 18°C for 84% of the night and morning period (23:00–09:00); relative humidity levels were above 65% for 46% of the time."
source_location: "Abstract (p.ii)"
- claim: "The mould index indicated that many homes show mould growth in bedrooms and/or bathrooms; these results indicate a lack of heating and/or ventilation causing mould growth, with potential adverse health effects. Air and dust samples were taken to determine the fungal spore content."
source_location: "Abstract (p.ii); §Observed mould"Neobiome Intelligence relevance
- Healthy housing — hard cold/damp/mould evidence. SR452 quantifies the room-scale conditions behind NZ’s housing-health problem: cold bedrooms (16.4°C) and high humidity (RH>65% for 46% of the time) driving mould. The 16.4°C bedroom corroborates HEEP2’s 16.5°C (OT_042), triangulating the cold-bedroom finding across independent NZ studies. Anchors the healthy_housing concept page. OT_048
- D04 — design implication. Mould is attributed to insufficient heating and/or ventilation — so a Neobiome build needs both a high-performance warm envelope and adequate ventilation (mechanical/heat-recovery), not just insulation; the RH>65% threshold is the mould-risk condition to design against. OT_048
Research targets
Research gaps
- The specific RH/temperature/dew-point thresholds and ventilation rates that prevent mould at the NZ bedroom scale (SR452 reports the problem conditions; the design solution thresholds — e.g. target RH, air-change rate — would let the model specify a ventilation requirement).
Connections
Links to
Sources (1): OT_042
Concepts (1): Healthy Housing — Warmth, Dryness & Wellbeing
Referenced by
Concepts (1): Healthy Housing — Warmth, Dryness & Wellbeing
EDT domains (1): D04: Sustainable Habitat & Building Technology
Sources (1): OT_133