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interpretation of the resulting images requires care and experience.
Figure 3 shows the thermal image of an exterior wall face of one of the blocks, focusing on the spandrel detail. The image on the left suggests an issue with rain- saturated polystyrene wall insulation in the concrete spandrel panels on the exterior of the buildings.
The colour and pattern in the thermal image is due to the irregularities in the insulation panels’ infrared thermal profiles, suggesting that the thermal insulation is wet in places.
As water-logged insulation is far less effective than dry insulation in providing a thermal benefit, the polystyrene panels were replaced as part of the renovation. The post-retrofit panels are notable by their even colour tones in the thermal image on the right of Figure 3.
Keeping tenants in the loop
Upgrading any building can be complex and subject to delays. Where tenants have to move out, there are costs to both landlords and tenants that are exacerbated if the original timeframes are not met.
The key considerations to good tenant management when upgrading are:
● keeping tenants informed
● working with tenants to jointly agree on
interim accommodation solutions
● keeping to upgrading timeframes and, if there is a delay, talking about it with
tenants
● not underestimating the costs to tenants
both nancially and, sometimes more importantly, socially. Many tenants will be part of a community based on the apartment building. Positive community attachments should be preserved.
Free landlord resources
Following this project, BRANZ has devel- oped resources to address the lack of good guidance for landlords wanting to upgrade and protect their housing investments.
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Figure 2: Number of days per year the indoor temperature gets critically cold (below 12°C) for apartments in di erent locations.
comfort. As well, energy use, such as lighting and space heating requirements, and heat transfer (heat gains from outside to inside and losses from inside to outside) were monitored.
Two tools – thermal simulation and thermal imaging – can help inform thermal upgrades planned by owners of apartment-style rentals. They are essential in understanding how existing buildings perform and the potential impact of di erent thermal improvements.
Modelling to get best design
Thermal modelling tools are computer programs in which a virtual representation of a building is constructed. A calculation engine then computes heat ows between internal zones as well as through the external building envelope over the relevant seasons, using historical hourly weather information and standardised user behaviour.
The implications of altering the build- ing’s physical layout, material properties such as insulation levels and orientation can be quickly and accurately explored. If used early and often to explore a variety of speci cation options, an optimal design can result. Simulation communicates the impact of design choices with more precision than would otherwise be possible.
Possible alterations to the Kotuku Apartments’ original external envelope were
explored with thermal simulation to assess year-round occupant comfort.
As one option, the number of days the apartments get critically cold (below 12°C) was examined assuming that space heating appliances were used.
This was particularly useful as initial enquiries found few tenants regularly used space heating during winter, with some never using it. Figure 2 shows when indoor temperatures became critically cold for di erent types of apartments before and after potential retro ts.
Interpreting results
Thermal imaging uses a special camera to help understand building performance issues in ways that would otherwise be di cult to nd. Thermal cameras make the invisible – the thermal anomalies – visible to the naked eye. With an experienced user, thermal imaging can be used to:
● nd thermal weak points and construction aws
● check the completeness of upgrading work ● identify with more precision building issues that are otherwise not visible, for
example, water leaks
● identify opportunities that can help in the
design to bring down projected energy costs. Although thermal imaging is a rapid way to identify areas of heat loss and moisture,
Build 161 — August/September 2017 — 79
Days temperature drops below 12°C in space