Air Quality in Newly-Built Homes

By k2ben | October 25, 2020

Residential construction in New Zealand is at levels not seen since the 1970s. The number of consents granted has been increasing since 2011. Since the 1970s, much has changed:

  • Building codes have tightened (insulation, double-glazing etc.)
  • Solid Rimu framing has been replaced by treated timber or steel
  • Materials containing asbestos are no longer commonplace
  • The leaky buildings saga has raised awareness of water-related issues
  • Earthquake-prone buildings have been identified and managed nationwide

This has improved building quality and safety in New Zealand. In many cases, materials used are also more environmentally friendly.

However, the way we currently build is not flawless.

Sealed Up

Modern homes are designed to be warmer and drier than in the past. This is achieved through numerous methods, such as:

  • Insulation (e.g. pink batts)
  • Double-glazing
  • Taping and stopping joins in linings
  • Building paper and membranes on the exterior of framing
Down and Out Is the Rule for Draining the Rain

These help improve home warmth, health and comfort. However, they can also reduce ventilation. This can reduce the ability for materials to dry if they do become wet, and reduces natural air ventilation rates.

Many also contain or release harmful compounds, either during the build or over time. Dampness in materials can exacerbate the release of harmful compounds.

Volatile Organic Compounds

Volatile organic compounds (or VOCs) are organic compounds that are easily evaporated at room temperature.

In new builds, these may be found in:

  • Treated or laminated timber (plywood, MDF, LVL)
  • Paints, glues and solvents
  • Carpets, vinyl flooring and soft furnishings

Health effects may be negligible, or brief exposures may have serious health effects. Exposure may occur during building, or after completion (off gassing).

Common Compounds and Cumulative Conundrums

VOCs in paint

Numerous compounds have been detected in indoor air quality studies; common ones include:

Formaldehyde

  • This can cause health issues at 0.1ppm (parts per million)
  • It may be off gassed by carpet or produced by cutting or heating materials
  • Chronic exposure can be carcinogenic

Benzene

  • This is a confirmed carcinogen
  • Low concentrations can cause drowsiness, headaches and heart rate increase

Acetone

  • This can irritate organs and cause unconsciousness in high doses
  • It has a strong, unpleasant odour (think nail polish remover)

Common Exposure Symptoms

Common exposure symptoms include:

  • Headaches
  • Eye, skin and organ irritation
  • Drowsiness
  • Long term exposure can cause organ damage, cancer and other health issues

Even at low levels, multiple compounds occurring together can cause health issues; this is known as cumulative exposure.

Benzene alone may have little effect. However, it often occurs alongside other compounds such as toluene, xylene, etc. Together, they may cause headaches, organ irritation or long-term damage.

Not Just at Home

Many compounds also occur in workplaces, increasing the likelihood of health issues.

  • A mechanic may also be exposed to benzene when working on a fuel system; they may also be exposed through paints off-gassing at home.
  • Formaldehyde is commonly found in processed wood products (LVL, MDF, plywood); it may affect builders, tradespeople, manufacturing staff etc. at work, as well as being emitted from those products at home.

Subsequently, managing indoor air quality at home is of high importance.

Vanquishing the Volatile

Reducing VOCs begins long before building is complete. Controls, however can be implemented to reduce or prevent VOCs in the home.

Elimination or Substitution

The best option in any case. Remove materials containing VOCs, or use low VOC products

  • Use screws instead of adhesives to fix plasterboard
    • Screw guns have made this process more efficient
    • Adhesives such as GIBFix One are low in VOCs if screws aren’t an option
  • Install heat pumps instead of wood or gas burners; combustion produces many VOCs
  • Apply low-VOC paint
    • The range of these is ever-increasing
    • Dulux, Resene and The Natural Paint Co have low VOC options
  • Use timber correctly treated for purpose, e.g. H1/1.2 for indoor framing
    • Limit the use of LVL, laminated wood products, etc.
    • Their overuse can also increase the overall price of the build
  • Opt for wool carpet instead of synthetic; think of the “new carpet” smell, that’s VOCs
New carpet in homes

Isolating VOCs

Like PPE, isolating VOCs is really only practical during building. VOC exposure should not be a hazard to the occupants of the completed house.

  • If expecting high indoor levels (painting, flooring), work outside or on another site
  • Close doors or maintain distance from sources if the above is not achievable
  • Staff working indoors must utilise all reasonably practicable controls to mitigate exposure; fumes in enclosed spaces can be fatal
  • Adequate ventilation or extraction should be in place
  • Limit work periods and take breaks away from the work area
  • Workers should use PPE; ensure correct filters are used on respirators and that they are properly fit-tested.

Adequate ventilation and air change is imperative

Adequate ventilation removes compounds produced through cooking or cleaning, and reduces excess moisture, preventing mould growth. It also manages off-gassing.

Healthy ventilation rates are 0.35-0.5 air changes per hour; excessive changes can remove heated or conditioned air.

Numerous means of improving ventilation are available, including:

  • Ventilation systems (HRV, DVS, etc.)
  • Security latches on windows to allow some air movement
  • Extraction in bathrooms, range hoods in kitchens

Understanding VOCs helps us manage them effectively

Managing VOC levels in the home is easy, provided controls are in place from day one.

  • Choose products with little, or no, VOC content; options for these increase by the day
  • Manage your work around painting or flooring contractors to minimise exposure
  • Utilise all reasonably practicable controls when using adhesives, solvents and other high VOC products
  • Consider air quality during designing; discuss this with your builder or architect
    • A few minor modifications can make major improvements
    • Even older homes can be fitted with ventilation systems such as HRV or DVS
  • Open windows if weather allows; some ventilation systems only run intermittently

By understanding and managing VOCs, your new home can be warm and dry without compromising indoor air quality.

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