REFRIGERANTS
HUMIDITY CONTROL
Dry facts about dehumidifi cation
Ranald Stewart, regional sales manager at Klima-Therm, answers your questions about dehumidifi cation.
Why is air humidity important to people and machinery?
Maintaining optimum humidity enhances people’s comfort, health, and wellbeing. If the air is too dry, it is more likely that building occupants will suff er dry skin, skin irritation, irritated eyes, and so on. On the other hand, excessive humidity can cause discomfort as well as promoting mould growth and bacteria and causing respiratory issues. Machinery can corrode if the air contains too much moisture. Humid air can also lead to faults and unreliability in electrical equipment caused by electrical shorts as well as production issues such as misfeeding paper in the printing industry. Too much moisture in the air can also adversely aff ect the integrity of stored materials.
What are the eff ects of humidity on building occupant health and comfort? Excessive humidity makes people feel sticky and the air feel heavy. People with respiratory issues can fi nd it diffi cult to breathe. High humidity makes it much harder for a
HVAC system to eff ectively cool the space as the moisture in the air resists the cooling process. This leads to longer cooling cycles, increased energy consumption, and higher electricity bills. Preserving the right humidity level helps
create a comfortable indoor environment and is especially important given the climate changes we’re facing. Typically, we’d aim for between 40 and 60% to create a comfortable environment.
What are the eff ects of humidity on HVAC equipment? Air with a high moisture content increases wear and tear on equipment, which then has to be replaced, causing unnecessary expense and disruption.
Intense humidity can cause moisture to accumulate in various components within the HVAC system humidity can build up in, for example, coils and fi lters which can lead to corrosion, mould growth and clogged fi lters, reducing the lifespan and effi ciency of the machinery.
32 September 2023 •
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Moreover, humidity causes condensation as warm, humid air passes over cooler surfaces like air conditioning ducts or vents. This results water damage and leaks which, in turn, can lead to structural problems in the building if left unaddressed.
What is the impact of humidity in diff ering environments of summer and winter? In summer, high humidity levels make it more diffi cult for our bodies to cool down through evaporation; in other words, we sweat less easily. As too the impact on our surroundings, high humidity in summer can contribute to mould growth and mildew, especially in areas with poor ventilation and this can damage buildings as well as aff ecting indoor air quality. In winter, we face low humidity because the
air can’t hold so much moisture. This can cause shrinkage of wood and furniture, can crack dry walls and, in a very dry environment, static electricity can build up.
What factors should contractors consider in order to achieve desirable room conditions? The starting point should be an assessment of the factors that are causing the issues, including general climate, local weather conditions, and location.
Secondly, fully evaluate the building’s insulation and ventilation systems. Good insulation helps regulate humidity levels, preventing excessive moisture from entering or leaving the building. A well-designed ventilation system can help maintain appropriate humidity levels. Thirdly, consider the size and layout of the
rooms. Larger spaces might require more humidity control measures than smaller rooms. Also, look at the types of activities that are taking place in the internal space. Many new build apartments, for example, incorporate gyms or swimming pools.
In general terms, why is dehumidifi cation important? Dehumidifi cation helps maintain optimal indoor air quality by reducing excessive moisture in the air. This reduces mould spores or musty odours and dust mites, all of which can negatively aff ect health.
Dehumidifi cation also plays a vital role in in
preserving the condition of the building fabric and its contents. High humidity levels can cause structural damage, warping wood, paint to peal, and so on.
Sensitive materials such as delicate electronics and artwork can deteriorate faster than they would if they were subject to a controlled environment.
What methods of dehumidifi cation exist and what are their advantages and drawbacks? The main methods are refrigeration-based dehumidifi ers and desiccant dehumidifi ers. The former work by refrigerating air over a cooling coil to condense moisture contained within the air. Their main disadvantage is that, from a control perspective, you can’t be really specifi c about the amount of moisture you’re removing so your parameters are wide. This type of dehumidifi cation can also be quite energy intensive, so it is more expensive to run. Desiccant dehumidifi ers use a hygroscopic material such as a silica gel to absorb moisture from the air. They are more effi cient than refrigeration-based dehumidifi ers and can operate a lower temperature. Their disadvantage
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