Articles for the Home Consumer

When Thinking About Your Ventilation Options, Consider Behaviour Too

If you’re thinking about your home ventilation options, consider a passive ventilation system as well as the behaviour of your home’s occupants.

Regarding occupants’ behaviour, did you know that building codes assume that your home’s windows will be opened regularly?

Stephen McNeil, BRANZ Building Physicist, reports that BRANZ’s WAVE (Weathertightness, Air quality and Ventilation Engineering) research has suggested that homes’ windows aren’t opened as often, nor as much, as is assumed by home designers and builders.

With people out at work and at school all day and returning home late, stale air inside our homes isn’t properly ventilated. How often do you throw open windows and doors throughout your home?

Home ventilation options and our behaviour: there’s little research

Although occupants’ behaviour affects ventilation, few studies have been done on it. Manfred Plagmann, BRANZ Senior Physicist reported that BRANZ researchers want to know why and how home occupants are ventilating their homes:

“As with many aspects of life, there is a trade-off. In this case, it is between cleaner air and energy loss. The recommended ventilation rate is about 0.4 air exchanges per hour to maintain a healthy indoor air quality.”

But why do home ventilation options matter?

Why your ventilation options matter: they’re essential to your family’s health

Breathing stale air is bad for you. Stephen McNeil, BRANZ Building Physicist reports:

“Ventilation is central to providing a healthy indoor environment. We constantly produce contaminants such as volatile organic compounds (VOCs), carbon dioxide (CO2), moisture, combustion products and cooking odours. Ventilation is the main means available to remove and dilute contaminants in the indoor air.”

Modern home construction methods aim at airtight homes, because airtightness offers us energy-efficiency. We conserve heat generated by our heating system in winter; in summer, we keep our air conditioner’s cool temperature inside, where we want it.

However, without adequate ventilation options, we may be endangering our health.

To improve your home’s air quality, throwing open your windows helps.

Next, evaluate passive home ventilation systems.

Passive home ventilation aims for continuous good air flow into and out of your home

But what’s “passive” home ventilation? Passive ventilation is a natural ventilation system that makes use of natural forces, such as wind and thermal buoyancy, to circulate air to and from an indoor space. These ventilation systems work to regulate the internal air temperature as well as bring fresh air in and send stale moist air out of the build envelope.

You have many options available. Stephen McNeil says: “passive ventilation options include trickle vents, passive stack ventilators and windows.”

What products are used in passive house ventilation?

Be guided by your roofing specialist, who will create a passive ventilation system specifically for your home’s requirements. This will ensure good airflow into and out of the roof cavity.

Expert guidance is essential, because the number and placement of products ensures that the system will work as intended, no matter how large or small your home.

For example, James Johnston, Commercial Manager of Vent Systems, discussed a passive ventilation system installed in a school which used a combination of only four products. He said:

 “The installed system features a G2500 over fascia vent, a VB20 vented batten, RV10P ridge vent, and a G1275 eaves comb filler—a combination of products that work together to ensure calculated airflow of 2500 mm square per linear metre of air passing through the roof cavity.”

You can also consider mechanical options.

Mechanical home ventilation options: extract and supply ventilation

Many homes have adequate ventilation with:

  • Open windows;
  • Range hoods and bathroom extractor fans; and
  • A passive ventilation system.

If these options aren’t enough, consider additional mechanical options. Stephen McNeil suggests that these can “include extract ventilation, supply ventilation and balanced ventilation with heat recovery.”

A house ventilation system needs both extraction and supply ventilation. Kitchen range hoods and bathroom extractor fans can manage extraction of heat and moisture.

Supply ventilation options are available too, if passive house ventilation can’t handle the load.

What’s involved in mechanical home air supply ventilation?

Stephen McNeil says:

“A supply-only system takes roof space air and ducts it to several rooms in the home through ceiling-mounted diffusers…

He maintains however that “a balanced system requires a very airtight building to be cost effective,” so it’s expensive when retrofitted.

Whatever ventilation options you choose, please be aware that you’ll need expert guidance to get the results you want.