Page 89 - Build 161

Departments/Research By Vicki White, BRANZ Data Analyst/Reporter
Are we warm, dry and healthy?
BRANZ’s latest house condition survey points the way to where improvements could be made to help achieve the goal of warmer, drier and healthier homes for all.
THE LATEST report on the 2015 BRANZ House Condition Survey (HCS) looks at some of the key requirements for maintaining a warm, dry, healthy home and the extent to which these are present in our housing stock.
Keeping the heat in
A home’s thermal envelope is the critical barrier between outdoor and indoor temperatures. Without insulation and other measures, such as draught proo ng and thick lined curtains on windows, heat loss can result in a cold, draughty indoor environment (see Figure 1).
A heated well insulated home not only provides a more comfortable living environment but New Zealand studies have shown an insulated warm home delivers tangible bene ts to occupant health.
Ceiling insulation levels suboptimal
Results from the latest HCS showed that most properties assessed did have some insulation in the roof space. Two-thirds (66%) had at least 70 mm covering at least 80% of the accessible roof space area.
However, this is well below the minimum recommended by the Energy E ciency and Conservation Authority (EECA), which recom- mends at least 120 mm ceiling insulation. Results from the HCS showed far fewer properties achieved this level, and some 47% of houses surveyed could bene t from additional insulation in the roof space (see Figure 2).
21–31% through the windows
12–14% through the oor
30–35% through the roof
18–25% through the walls
6–9% through air leakage
Figure 1: Heat loss through an uninsulated house.
Opportunity to improve sub oor insulation
The sub oor is another area that can o er substantial bene ts in home performance if properly insulated. When considering the e ectiveness of sub oor insulation and the potential for retro t, the coverage (area of habitable oor space insulated) and material used are important considerations.
The 2015 HCS found that, in properties with an accessible sub oor (around two-thirds of all houses surveyed), nearly one- fth had no insulation or insu cient coverage. Forty-three percent had good coverage of bulk insulation (see Figure 3).
A further 18% of sub oors had foil insulation (12% of all houses surveyed). Foil performs far less e ectively as an insulating layer.
Build 161 — August/September 2017 — 87