Apartment upgrade

This Issue This is a part of the Medium-density housing feature

By - , Build 154

BRANZ Is monitoring an ageing Wellington City Council apartment block during a major upgrade to establish building performance and occupier satisfaction. This will give valuable advice for other apartment upgrades.

An early 3D representation of the Kotuku Apartments, looking west.
An early 3D representation of the Kotuku Apartments, looking west.
Conducting a heat flow experiment measuring the thermal transfer through the building envelope.

BRANZ IS ENGAGED in a multi-year project looking at how to renovate low-income rental dwellings to get the best outcomes for occupant health, comfort and satisfaction when there are financial constraints.

Little info to help upgrades

The rental sector has many houses that perform poorly in terms of occupant health, comfort and satisfaction, particularly those occupied by low-income tenants. However, there is a lack of good guidance for landlords who wish to upgrade and protect their housing investments.

While plenty of new housing is needed in New Zealand, most of the current stock will be in use for years to come, making housing retrofits an important industry sector.

Kotuku Apartments upgrades

Wellington City Council offered BRANZ a number of its rental properties to use as case studies for the project. The multimillion dollar Kotuku Apartments upgrade was chosen.

The apartments are located in Kilbirnie. near Wellington airport. Consisting of four 4-storey buildings built in the 1960s, the apartments are part of a multi-million dollar upgrade over the 2013–17 period.

The upgrade includes considerable improvements to:

  • the internal fixtures and appliances
  • the thermal envelope of the building – the windows, walls, roofs and floors
  • the external landscaping and hardscaping such as paving and driveways.

On the technical side, BRANZ has been monitoring various performance aspects including:

  • indoor temperature and humidity for assessing occupant thermal comfort
  • energy end use such as lighting and space heating requirements
  • heat transfer – heat gains from outside to inside and losses from inside to outside
  • performance of the thermal envelope.

Understanding what the tenants think

On the social-behavioural side, CRESA (Centre for Research Evaluation and Social Assessment) has been engaged to help understand tenants’ energy-related behaviour and experiences with the upgrades.

Conducting a heat flow experiment measuring the thermal transfer through the building envelope.

BRANZ thermal modelling

A key part of the study is to understand how much the thermal upgrades have improved the overall thermal comfort for the occupants. This is not just during winter but year round to include overheating in summer.

For this, BRANZ has thermally modelled the original and proposed renovation plans of the apartments to compare expected thermal performance. The modelling results show that the upgrades will, theoretically, make a massive improvement.

To see how this matches with reality, BRANZ is also undertaking a suite of on-site thermal tests, including thermal imaging and elemental and whole-building heat flow.

To further strengthen understanding of the issues, the tenants' perceptions of the building’s thermal attributes will also be examined.

Results will inform smart upgrades

The project should improve the understanding of smart upgrades for low to medium income housing providers such as councils, Housing New Zealand and community housing groups.

The short and longer-term field studies will finish in September this year. The findings will be shared through Build and as part of a national summit early in 2017.

BRANZ would like to thank Wellington City Council’s City Housing team for facilitating and supporting this important project.

For more

Contact Roman Jaques at [email protected]

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Articles are correct at the time of publication but may have since become outdated.

An early 3D representation of the Kotuku Apartments, looking west.
An early 3D representation of the Kotuku Apartments, looking west.
Conducting a heat flow experiment measuring the thermal transfer through the building envelope.

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