How house type affects energy retrofits

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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. 

The ten house types are:

Early housing (pre-1890)

Early housing example

Ease of retrofit will depend largely on access to ceiling and floor

Villas (1880-1920)

Villa example

Good retrofit candidates for better   energy performance

Bungalows (1920-1940)

Bungalow example

Good retrofit candidates for better   energy performance

Art deco (1925-1935)

Art deco example

Likely to require moderate to   considerable effort and cost to energy retrofit

State houses and mass housing (1930-1970)

State house example

Good candidates for energy retrofit,  particularly the 50’s classic

1960’s and early 1970’s multiunit houses

1960s-70s multi-unit house example

A challenge - likely to require   considerable effort and cost to energy retrofit

 

 

1970’s housing (1970-1978) pre-insulation

1970s house example

Wide variation in styles and   generally moderately easy to energy retrofit

1980’s housing (1978-1989)

1980s house example

Wide variation in styles and   generally moderately difficult to energy retrofit

Early 90s (1990-1996) pre-revamped Building Code

1990s house example

Wide variation in styles and   generally moderately difficult to energy retrofit

Last decade (1996-2007) post-insulation upgrade

Last decade house example

Daunting retrofit option. Each case must be judged on its merits.

   

 


  • 30-Apr-2010 (Conference paper EN6570/10)

    It Takes All Types: A Typology of New Zealand Housing Stock (PDF 3MB)

    Ian Page, Verney Ryan

    SB10 New Zealand


  • 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.


  • 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.