Living and dining rooms
Living and dining rooms typically have more floor area per person than bedrooms, and we spend less time in living rooms than in bedrooms. This makes it easier to provide adequate ventilation of living rooms. The ventilation must often meet comfort requirements (feeling of fresh air) rather than health requirements. The need for ventilation in a living room can change from low to very high (with guests in the house), and the ventilation design must reflect that. A flexible ventilation design includes two to three operable facade windows and a similar number of roof windows to allow efficient airings when the need is high. Manually operated windows may be sufficient if ventilation flaps are used in combination with a reasonable use of airings. Electrically operated windows can provide additional peace of mind.
Activities in the kitchen generate humidity, smell and fine particles, all of which are most effectively removed by efficient ventilation at the time of the activity. Cooking hoods are important, but their performance is reduced as they get dirty from grease, and airings while cooking is a good habit and an efficient supplement. The airings are most efficient when windows located at two different heights can be opened, e.g. facade windows and roof windows. Due to the heat generated by ovens and stoves, cold draughts are rarely a problem in kitchens. As the need for ventilation is usually easy to sense and smell, it is simple for occupants to make airings at the right time. Humidity-controlled electrically operated windows can be an additional benefit.
Bathroom activities produce humidity and smells. Humidity generation is high during baths, but bathrooms are not used much during a 24-hour cycle. An efficient ventilation design, therefore, allows high ventilation rates for short periods. Bathrooms are often equipped with mechanical extract ventilation, but good possibilities for airings are an advantage. The most efficient airings are achieved with windows at two different heights. As the need for ventilation is usually easy to sense and smell, it is simple for occupants to make airings at the right time. Humidity-controlled electrically operated windows can be an additional benefit.
Natural ventilation exhaust path
In houses with natural ventilation, it is important to consider the flow path of the air in the house when it is renovated. The flow path depends greatly on wind direction, wind speed and external temperature conditions, and a specific window can function both as inlet and extract. However, high-placed windows (and stack ducts) will function mainly as extracts. In one-storey houses, roof windows in kitchens and bathrooms will often function as extracts and will ensure that air is generally taken into the house through bedrooms and living rooms and extracted through wet rooms.
In two-storey houses, windows at the upper level will often function as extracts. If bedrooms are located on the upper floor, it is important that bedroom windows are not used as extracts, as this may cause overheating and will increase the risk that the air entering the bedroom is from other rooms in the house and therefore less fresh. An efficient solution is to place a roof window above the staircase on the upper floor, as this window will often function as an extract for the lower level.