What is ventilation, and how does it work? What are the regulations that support ventilation? How can I improve the ventilation in my centre? You will find answers to these questions and more in this article. Ventilation is simply the flow of fresh air into a room and stale air out of that room. Good ventilation is a crucial tool to ensure good indoor air quality (how fresh the indoor air is) and thermal comfort (how comfortable a room feels). Research has repeatedly shown that poor ventilation leads to short-term and long-term health issues (Wargocki et al., 2002). With children estimated to spend up to 85% of their time indoors (Lum, Jenkins, & Shimer, 2013), good indoor air quality and thermal comfort are therefore vital. Younger children are also more vulnerable than adults to indoor environmental effects. This is due to their faster breathing rates and their larger lungs in proportion to their body sizes as well as their rapid growth and undeveloped bodies including their immune systems, eyes and ears (Bennett, Zeman, & Jarabek, 2008; Fuentes-Leonarte, Ballester, & Tenias, 2009; Tomita, Shichida, Takeshita, & Takashima, 1989). So how do we get the air moving in a centre? There are two ways – mechanically, using Ventilation – a hot topic By Phil and Tiffany Smith, Smith Architects Gaia (Earth) Forest Preschool NZ. Photography by Tessa Chrisp mechanical ventilation systems or naturally, using the building itself to naturally ventilate the building by opening windows and doors. creating cross ventilation as it moves across the room. Other building techniques that encourage airflow through a building and between rooms is a 25-50mm gap between the floor and the bottom of all internal doors (called an undercut) and using barn-styled doors between rooms so that the top half may be left open while keeping the children in the room. In New Zealand, The New Zealand Building Code G4 Ventilation defines the minimum and only legal requirements that a building must comply with. With most Early Learning Centres being naturally ventilated, a centre only needs to have “a net openable area of windows or other openings to the outside of no less than 5% of the floor area”. While this regulation considers room size, it does not consider room depth nor how much you can open that window. Therefore, if you have a deep room or windows that can only open a small way, consider installing a CO2 sensor to check that the air at the back of your room is being refreshed. If CO2 is building up at the back of the room, you may also find that the room has poor natural daylight. If this is the case, there are now openable skylights available from Velux that have built-in CO2 sensors which open When using mechanical ventilation systems, it is critical that they are cleaned and serviced annually and that the extract vents of the system are regularly checked to ensure they are free of the dust and fur that grows on them. Natural ventilation can only happen when there is at least one opening to the outside of a room. The opening can be a door or a window. As a rule of thumb - a room will only be adequately ventilated to the back of the room if the room is no deeper than 2.5 times the height of that opening. If the room is deeper than 2.5 times the opening, then this room will ideally need to be cross ventilated; that is, an opening is needed on the opposite wall. When two openings are opposite each other in a room, fresh air is pulled through one opening and sucked out the other One thing to note is that a heat pump is NOT a ventilation system – a heat pump only heats up or cools the air already in the room. When using a heat pump, it is essential always to have a window or door ajar to allow stale air out and fresh air in. December 2022 { 24 }
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