INDOOR AIR QUALITY AND HEALTH

An Analysis of the Indoor Air Quality and Health in New Zealands Homes

Holger de Groot

A master thesis submitted in fulfilment of the requirements for the degree of Master of Architecture

ARCHGEN 793A and 793B

School of Architecture and Planning, University of Auckland Auckland, New Zealand

2009

INTERVENTIONS AND REFURBISHMENT 113

wall components of different house typologies can only improve housing condition in terms of

IAQ and comfort when realized in combination with:

roof insulation

underfloor space insulation

double glazed windows with thermal break joinery

acceptable ventilation rate / system

heating system

This combination can guarantee a higher thermal comfort within these houses besides IAQ

improvement and a higher building energy performance. Additionally, when combined with a

mandatory rating system for existing residential buildings, such retrofitted homes may also

have a premium value in the market place which will be reflected in the value of homes at on

sale or rental. 8 Therefore, this thesis will now provide practical recommendation and retrofit

solutions for refurbishments of specific building typologies, built between 1950 and 1980s.

9.2. LABOUR STATE HOUSES (1930 - 1970)

According to Beacon, the labour state housing typology can be rated as a good candidate for

retrofit packages but most occupants are still of the lower income group with large families. 9

Therefore, maintenance and renovation options in the past and present are restricted by the

financial ability of the homeowners or a leak of public founding from the government. These

circumstances lead to the current situation that many labour state houses suffer under

dampness and mould growth which may require e.g. to remove and to replace the internal

gib lining. Regarding this, it is necessary to assess the extension of damage before

introducing a retrofit package.

The design of the labour state house can allow upgrading the construction relatively easy

(refer to figure 9.1). For example, the steep roof of the English cottage style design is usually

built with maintenance holes that are placed in the ceiling panels. These make the existing

roof space accessible for insulation addition. Furthermore, when the house is located on a

slope site, the underfloor space is mostly accessible and offers the opportunity to be

insulated from the outside. When located on a flat site, the house is usually built with a

ventilated foundation wall which can limit the access to the floor construction from the

outside. In this case, it is necessary to create a small access point in the foundation wall to

be able to retrofit the ventilated underfloor area with insulation material. Apart from the roof

8 New Zealand Business Council for Sustainable Development (NZBCSD), A-2008, p.39. 9 Verney Ryan. Building Momentum for Sustainable Homes, Symposium 2008: Turning serial

renovators into sensible retrofitters. Auckland, New Zealand: Beacon Pathway Ltd, 2008, p.6.

INTERVENTIONS AND REFURBISHMENT 114

and floor construction, also the standard window units which were used for the original labour

state house design offer now a high flexibility to replace the existing windows with double

glazed units, including new framing. Regarding this, it is recommended to install double

glazed windows with timber frames combined with aluminium protective profiles on the

outside. Interventions on different external wall construction of labour state houses appear

instead more complicated. Generally, a retrofit package has to be suitable to the existing

cladding system, regarding the labour state house design which made use of three different

cladding systems: (a) weatherboards, (b) asbestos cement sheets or (c) brick veneer. 10

Figure 9.1

External Wall of the Labour State Houses

The external wall of the labour state houses

are typically covered with (a) weatherboards,

(b) asbestos cement sheets or (c) brick veneer.

Inside the house, the walls are normally lined

with fibrous plaster and finished with wallpaper.

Therefore, different retrofit packages will be

proposed and tested for each cladding system.

10 Refer to chapter 6, pp.70-73.