Thermal Comfort

In a perfect world, all classrooms would be naturally ventilated, maintaining a constant temperature throughout the day. In the real world, this is seldom possible. We have to introduce a balance of natural and artificial features in order that the pupils learning environment in the classroom is not affected by adverse room temperature.

Average Classrom Temperatures

In a perfect world, all classrooms would be naturally ventilated, maintaining a constant temperature throughout the day. In the real world, this is seldom possible. We have to introduce a balance of natural and artificial features in order that the pupils learning environment in the classroom is not affected by adverse room temperature. The average standard classroom temperature is around 18 degrees Celsius but may vary according to local climates. Extreme temperatures distract the learner and affect their concentration levels. It goes without saying that in a cold climate, a classroom has to be warmed and in a hot climate, a classroom needs to be cooled. The challenge is to achieve the desired temperature by using as little energy as possible. This usually involves clever design taking into account solar orientation, natural light and natural ventilation. It also involves introducing features to complement existing natural features.

Louvre’s, Overhangs, Awnings And Trees

Shading is more effective to block the suns heat from reaching your classroom window or wall than dealing with the heat once it has entered the room. Shading does the job without compromising natural light entering the classroom.  Shading may be provided by a shading system or feature design that allows flexibility for seasonal changes or daily weather changes that may occur. For example, in the Southern Hemisphere, North facing windows should be shared with devices that provide protection from the summer sun and, where required, allow the sun to enter the building in winter. In this case shading can be provided by adjustable fabric pergolas, awnings, louvre’s, shutters or trees.

Here is some food for thought – external shading is much more effective in keeping your classroom cool than internal blinds or shutters.

Glazing Or Windows

The location and placement of windows in a classroom have a direct effect on the thermal comfort. The type of glass used has a direct effect on heat retention and rejection plus natural light filtration. Hy These days building regulations specify a minimum requirement on the combined effect of glass and frame. Each country is different, refer to your countries building code regarding glazing to check if the current windows in your classroom comply. There a may also be specific requirements for your countries climatic zones.

The U-Factor – sometimes referred to as U-value or thermal transmittance, addresses the ability of glass to harness and retain heat in differing climatic conditions. Double glazing is widely considered to offer the best insulation in most climates. It is basically a window consisting of two glass panes separated by a hermetically sealed air or gas filled space typically between 6mm and 20mm apart.

Wall and Ceiling Insulation

Insulation in classrooms reduces the need for additional power use to heat or cool a classroom by “smoothing out” the peaks in energy demand. Insulation effectiveness is rated by its R- value which is a measure of thermal resistance within a school building. Thermal resistance is a heat property and a measure of a temperature difference by which an object or material resists a heat flow (heat per time unit or thermal resistance). The greater the R-value, the better performance from the product in retaining heat in winter and expelling heat in summer. A well-insulated school building and its classrooms reduces reliance on artificial heating and cooling systems, making the learning environment healthier and more eco-friendly.

Evaporative Air Coolers

Evaporative coolers are often installed in classrooms as a more eco-friendly alternative than conventional air-conditioning units. Air conditioners pump refrigerant (which produce emissions) through compression and evaporative cycles to cool building interiors. Evaporative cooling systems chill flowing air by evaporating water. They work particularly well in hot dry climates and generally more energy efficient than an air-conditioner. They use around 60% less electricity than comparably sized refrigerant-based air-conditioning systems.

There is also no need to close doors and windows when the evaporative cooler is in use. The cooler operates with cross ventilation exchanging indoor air with natural outdoor air

Chiller Plants and HVAC Systems

Some schools are situated in high rise buildings in the inner city. These buildings typically have a central ‘Chiller Plant’ combined with an ‘HVAC System’ which is used to maintain a desired temperature throughout the building. A Chiller Plant is really a very large air-conditioner while HVAC stands for heating, ventilation and air conditioning.

The HVAC system ensures safe and healthy conditions are maintained with respect to air quality and comprises a series of ducting systems running throughout the building. It is through this controlled system that unwanted or polluted air is also extracted out of the building. It goes without saying that these large systems use a lot of energy. Usually, school management and maintenance staff ensure that the classroom temperature remains constant. At the same time, regular monitoring and maintenance ensure that energy use is kept to a minimum.  It is also important to know that the HVAC system also forms part of the fire protection end prevention in a building.

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