All the truth about condensation

The physical phenomenon Condensation is caused because the air in the room contains a certain amount of steam which can come from various sources – from people, the shower, the kitchen and so on. The amount of water that the air can contain depends on the temperature: the higher the temperature the more water that […]

The physical phenomenon

Condensation is caused because the air in the room contains a certain amount of steam which can come from various sources – from people, the shower, the kitchen and so on. The amount of water that the air can contain depends on the temperature: the higher the temperature the more water that can build up in the air. In the hypothesis of air saturation, i.e. the maximum amount of water that can be built up, when the temperature drops the steam is transformed into drops and this transformation phenomenon is called condensation.

Inside the home

The air is never saturated but just contains a certain amount of water which is called “relative humidity”. In modern homes it is very difficult for condensation to form, because humidity is well controlled and technology is widely used in the riskier situations to prevent it forming. For example, let us consider the kitchen ranges of the past where the food was cooked for hours on end, as opposed to the controlled cooking times today with sophisticated suction hoods installed. Rather nowadays we often even have to put humidifiers in the rooms because the air has become too dry!

Condensation can be prevented with a few simple remedies to reduce the relative humidity in the room: it is a known fact that the humidity must never be completely removed from the air – it just needs keeping under control to prevent condensation forming – as a humidity level between 40% and 50% in the air is the perfect environment for people to live in.

The first thing we can do is to improve air exchange in the rooms, for example opening the window for a few minutes, especially after a shower or bath or cooking for a long time. Humidity can also be reduced by modern air-conditioners which are commonly used to cool down, heat up and dehumidify the air as well. Air conditioning can also be the answer in older buildings as well.

We can also alter the window frames to improve heat proofing but this is the least advisable remedy, because it does not effectively reduce the humidity in the room. However, when a window frame is being made glass must be adopted with high heat-insulation features as this drastically reduces heat dispersion outwards.

So why was thermal break invented?

The thermal break systems were originally designed for use with aluminium profiles, to help save heating and cooling costs because aluminium is an excellent heat conductor and has always had the problem of heat dispersion inwards and outwards. If we then consider the large width and depth of aluminium profiles needed for the frames, we can easily understand the extent of the heat insulation problem in this type of product.

So, contrary to common belief, thermal break systems were not invented to prevent condensation forming on the inside of the frame, but to make up for the specific failings in aluminium. A failing that has created an enormous business because a basically unsuitable product for a window frame can be sold at a very high price – because it is dimensioned according to the weight of the boxed profiles – but without giving the heat insulation and seal that are instead required from quality frames.

Nowadays thermal break installation is generally requested to prevent condensation forming on windows and doors and to reduce heat dispersion between inside and outside, brazenly incorrect clichés that just make us spend money without effectively solving the problem. Because thermal break profiles do not solve the problem of high humidity levels, which is the real cause of condensation, they just move it elsewhere, in fact the excess humidity in the room will just settle somewhere else and not on the frame, perhaps causing mould on the walls or impregnating the upholstery, curtains or mattresses and, worse still, give rise to rheumatics in the inhabitants!

It is very important to understand what is the best investment to prevent condensation, which, as we have already said, is less of a problem in modern homes, except at particular times (in the bathroom after a shower, in the kitchen during long cooking sessions) and can easily be prevented by ventilating the rooms.

Consequently to understand whether thermal break profiles are needed or not, in line with current energy saving regulations, we must do a calculation using the thermal transmittance formula the UNI EN ISO 10077-1 February 2002 standard refers to, which is valid throughout Europe.

The use of iron or stainless steel profiles, which have much lower thermal transmittance levels than other materials, often prevents the need for thermal break: in fact, with the same size frame these profiles are much stronger and much smaller than aluminium ones and in percentage terms cost less. It is often more convenient to use profiles without thermal break and invest more to decrease the transmittance in the glass, because that is the largest surface area of the entire window and consequently has a greater effect on overall wellbeing. This way heat insulation levels are obtained that are much higher than those given with thermal break profiles with less-insulating glass.

Therefore to ask for thermal break is not automatically the best choice. There is the best solution for each single case, which must be evaluated from time to time to ensure that a long-lasting item like a window frame, which has to last as long as the entire building, is efficient in the long term and therefore a good investment.

Expertly used and machined steel is the only material that can guarantee all this.

Giulia Sartor

Acciaio Arte Arrchitettura 34

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