Our revised ZE home

Revised ZE home

FMI’s ZE home - Revised

The shape and size of the home we modelled was the same as our original one analysed in the first issue of Fenestration New Zealand. It remains a modest, standalone three-bedroom family home of 120m2, aligned with typical New Zealand construction. Passive design strategies such as optimised window placement were not considered. It houses four occupants who are frugal with hot water. We did, however, experiment with building components to develop a Revised home. Improved airtightness was a new goal we set ourselves.

The key differences between the Original and the Revised home are set out in Figure A.

FIGURE A:

FMI ZE/R Original and Revised Builds Compared

COMPONENT ORIGINAL ZE/R

Windows

R 0.8 (modelled on as-built 0.72)

Insulation

Air-tightness

Fibreglass batts with a product rating high enough to deliver required as-built performance Spray foam insulation for both simpler installation and increased performance

None. Air changes per hour (ACH) of 5 Air changes per hour of 2 via: Very high-performance windows with reduced air leakage. Exterior air-tightness layer such as OSB with liquid applied weatherisation. Balanced ventilation system with heat recovery.

Floor

Concrete pad

REVISED ZE/R

R 0.95 installed with four-sided thermal installation method.

Timber, to increase the range of section profiles it is feasible to build on.

In the modelling for the Revised house, we kept to As-Designed R-values rather than As-Built because this appeared to be in line with MBIE’s approach. It was an oversight that led us to model a temperature range with a minimum of 200C instead of MBIE’s 180C. The warmer temperature placed a higher energy demand on the ZE house. This played to our advantage: it increased the robustness of our Revised ZE home’s strong performance against the MBIE build options.

Designed to withstand New Zealand’ s climates, in cold areas our solace Low coating allows the sun ’ s light and energy into your home reflecting the heat back indoors. In warm areas temperature can regulated by changing the positioning Low-E coating within the glazing unit