Dew Point
Mold growth, corrosion under insulation (CUI) and condensation damage in the building envelopes and mechanical piping systems are most often the result of atmospheric water vapour reaching the dew point and condensing back into liquid water. This type of hidden moisture stays on the surfaces of steel pipes and inside the interior wall assemblies, wreaking havoc through structural decays and rots, degrading and rusting metal components and eventually resulting in the exponential increase of biological contaminants in indoor environments. Water leaks are easy to pinpoint but not moisture, which is hidden and escaping visible detection while continuously causing significant damage within the wall cavity, inside ceiling, beneath flooring and under the roofing system. Higher energy cost is another ramification of interior dampness as the soaked insulation material is rendered ineffective and as a consequence additional HVAC load would be needed in order to cool the area. Thermal resistance of fibrous insulation materials is greatly compromised when wet, resulting in the gradual degradation of its insulating performance over a period of time.
Dew point is defined as the temperature at which air is saturated with moisture to the point that water vapour condenses back into liquid form. In this scenario, air can no longer hold any more vapour when the relative humidity is at 100% resulting in water droplets forming on the surface. The closer the difference between the actual surrounding air temperature and the dew point, the higher the relative humidity would be. A glass of cold beverage taken out of the refrigerator would cause the surrounding moist air to be instantly equal to or below the dew point, liquid droplets would then form on the glass surface as it condenses. This principle also explains how fog and morning mildew on grass develop.
In the context of designing the insulation system, it is imperative that the dew point of the surrounding air be considered to avoid interstitial condensation and its resulting risks. This is especially more pronounced when it involves structures near the sea, when the surrounding air is very humid or a cold storage facility wherein maintaining the ideal temperature is crucial. A colder environment means that the ability of the air to hold on to vapour moisture decreases, therefore the likelihood of condensation builds up. Having the right insulation is one way to prevent moisture intrusion on assemblies by elevating the surface temperature and keeping it in consonance with the surrounding air, thus moving the ambient temperature above the dew point. Insulation does not affect the dew point, but prevents the surface areas from moisture ingress by keeping the surface temperature above the dew point, thereby greatly minimizing the potential for condensation inside facilities and building structures.
A properly designed and installed insulation system is moisture preventive and thermally efficient. Knowing the temperature gradient of a surface and the corresponding dew point will help in creating the right insulation layer that would keep moisture from infringing and intruding into the critical sections of the wall assemblies or piping structures.
Patsum insulation can help you and your business grow through the use of the right insulation solutions that can mitigate moisture and fire risk at the same time create an environment that is energy and acoustically efficient.
