How house type affects energy renovation
There are 1.6 million existing homes in New Zealand, many of which are underperforming. Insulation, as an example, is specified at high levels now for new houses, but many existing homes are still inadequately insulated. Estimates indicate:
- 18% (250,000) of houses have no ceiling insulation at all, or insulation in less than half of the roof area
- 60% of houses (900,000) have ceiling insulation of inadequate thickness when compared to the 1978 Building Code
- 700,000 houses have no, or little, wall insulation
- 740,000 houses with suspended floors have no underfloor insulation
To improve the energy performance of so many houses, we’ve broken them down into basic house types. Even though New Zealand’s climate varies from the top to the bottom of the country, the same basic housing types in each period of history were used throughout the country for mass housing. In the main these were timber framed houses with metal roofs and little or no insulation. As shifts in society and culture occurred, including updates to the building regulations, changes appear in house typology.
Our aim is to cover 80% of New Zealand’s housing stock within ten house types. By understanding how each type of house was built, we can identify the issues and challenges that energy renovation will have to address. We’re asking:
- What housing typologies are easiest to retrofit, and what proportion of the overall housing stock do they make up?
- What energy efficiency gains are possible within the constraints of individual dwelling typologies?
- What parameters make a house not worth retrofitting and how can those be defined?
The ten house types are:
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Early housing (pre-1890)
Ease of retrofit will depend largely on access to ceiling and floor |
Villas (1880-1920)
Good retrofit candidates for better energy performance |
Bungalows (1920-1940)
Good retrofit candidates for better energy performance |
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Art deco (1925-1935)
Likely to require moderate to considerable effort and cost to energy retrofit |
State houses and mass housing (1930-1970)
Good candidates for energy retrofit, particularly the 50’s classic |
1960’s and early 1970’s multiunit houses
A challenge - likely to require considerable effort and cost to energy retrofit
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1970’s housing (1970-1978) pre-insulation
Wide variation in styles and generally moderately easy to energy retrofit |
1980’s housing (1978-1989)
Wide variation in styles and generally moderately difficult to energy retrofit |
Early 90s (1990-1996) pre-revamped Building Code
Wide variation in styles and generally moderately difficult to energy retrofit |
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Last decade (1996-2007) post-insulation upgrade
Daunting retrofit option. Each case must be judged on its merits. |
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31-Oct-2008 (Report EN6570/9)
New Zealand House Typologies to Inform Energy Retrofits (PDF 651KB)
Verney Ryan, G Burgess, Lois Easton
This report outlines the methodology and work undertaken to develop a series of housing typologies to inform Beacon in relation to energy retrofit interventions. It outlines the findings from a workshop examining house typology and a process of engagement with key experts to develop a framework for definition of house typologies applicable to the New Zealand housing stock.
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31-Oct-2008 (Report EN6570/8)
Housing Typologies: Current Stock Prevalence (PDF 392KB)
Ian Page, J Fung
This report analyses the characteristics of the housing stock (such as roof space and sub-floor space access, existing insulation levels, window and wall cladding condition, etc) that affect the ability, opportunity and need to retrofit sustainability features. The report confirms the typologies developed in earlier work are generally useful and numbers in each group are provided.