Coolzy is designed to work in a room with ventilation. We recommend that you keep a door or window open while using Coolzy.

Using Coolzy in a small room without effective ventilation can warm the upper part of the room significantly. This will be even more obvious in a room with a low ceiling or with well-insulated ceiling and walls.

A person lying on a bed may not notice this with a blanket of cool air coming from Coolzy. However, a standing person may feel some discomfort because the temperature at head height can be 3 – 4 °C warmer.

If the door and windows must be closed, we recommend installing a split air conditioner. A dual-pipe portable room air conditioner may also work in this situation. A portable room air conditioner with a single exhaust pipe will provide some cooling (about 3 °C) but will probably be too noisy to sleep with, and also will use much more electricity.

Sometimes, opening a window may not be possible. We have seen rented rooms where the landlord has permanently locked the windows closed. We have also seen windows near a hot outdoor exhaust from a large air conditioner. In other situations, a desire to exclude light or for privacy may require keeping curtains or blinds closed.

Here are some suggestions to improve ventilation using a low-cost electric fan. We tested some of these arrangements and we have shared the results with you on this page.

We tested Coolzy in a small bedroom 3 m x 3.5 m (10 ft x 11 ft), equivalent to a small bedroom size in many homes. The bedroom walls are plasterboard on timber frames, and the ceiling and outer walls are well insulated.

We performed the tests between 3:30 pm and 8 pm in summer when our building reached its maximum daytime indoor temperature, 36°C. All the external doors and windows were kept closed during the test.

We restricted the room ventilation. For the first test, the door was wedged with an opening of 30 cm to provide privacy for the occupant and the window was closed.

We ran our Coolzy-Pro for an hour before collecting measurements.

The fan was outside the door of the room in the passage way, directing cool air from the floor level of the passage air through the lower part of the door opening. Warm air leaves the room through the upper part of the door opening.

Without the fan running, the temperature in the upper part of the room increased by 3 – 4 °C.

With the fan running, the upper part of the room was only 0.5 – 1 °C above the building temperature, a large improvement.

Following this, we tested a second arrangement in which the fan is placed inside the room, blowing air at the top of the window. In this test, the sliding external window is open and the fan is aimed at the top of the insect screen in the open section of window to the right side. Here’s a drawing and a photograph.

After running this test for an hour, the upper part of the room was less than 0.5 °C warmer.

The door was closed for this test. If the door had been open, air would also come in through the doorway.

Other Fan Arrangements

There are many ways to use a fan for effective ventilation.

For example, you can set up the fan to blow air through the top of a doorway so that warmer air in the top half of the room is expelled through the upper half of the doorway. Some air will enter through the lower half of the doorway if the window is closed.

In the next arrangement the fan is placed outside the window to blow air through the insect screen. Make sure that the fan is sheltered from any rain that could fall.

Note that if the door is closed, it is important to ensure that air flows in one part of the exposed insect screen and out through another part if there is only one window.

You can easily observe slow air movement to test your fan arrangement. Smoke from a cigarette will reveal any air movement. Another way is to use a piece of a spider’s web. Catch some spider filament on the end of a pencil or piece of wire. The loose end of the filament will reveal the slightest air movement. Remember that air may move one way through the upper part of an open door or window and another way through the lower part.