Condensation on windows occurs mainly due to a high moisture content in the large office area. When the warm and humid air comes into contact with the cooler glass surface, its temperatures drop suddenly. Therefore, the air cannot hold any more vapour leading to condensation on the glazed windows (Branz 2017). In this case, the mechanical cooling and heating systems serving the in the vast office space are the primary sources of the high indoor humidity besides the moisture released by the office occupants. Notably, the AHU unit currently being used has many VAV boxes, employs steam heat, and moisture, as well as a DX cooling system which collectively increase the internal air vapor. According to the IAQ (Indoor Air Quality) toolkit, the recommended moistness for office spaces should be about 50% (Alberta 27). At this level, condensation is not likely to occur even during winter. Higher humidity levels of between 50- 60% make the air stuffy as well as encouraging condensation. On the other hand, when the moisture drops below 20%, the air becomes extremely dry thus causing static charges on the windows and other office equipment (Alberta 27).
First, I would recommend a review of these HVAC systems to determine whether it is possible to reduce the amount of moisture content that they produce. Such could be achieved through the use of a simple sling psychrometer or hygrometer to monitor the relative humidity continually (GreatDay 2018). Once the actual statistics of the internal air quality are established, the amount of steam released by the AHU components can be adjusted accordingly. For that reason, moisture-generating devices like humidifiers should not be operated during the cold weather (Becker 127). Further, the use of dehumidifiers which heat up the indoor space thus eliminating the excess water vapor would prove to be a viable solution. This is because, by raising the internal temperatures, the surface of the windows consequently gets heated hence reducing the level of condensation on them. To further boost the temperature of the windows, drapes or blinds can be employed. If there are indoor plants within the office spaces, they should either be eliminated or restrict their watering (GreatDay 2018).
Secondly, the use of ventilation strategies would significantly help get rid of the vapor-laden air from the internal office spaces. To begin with, ventilation fans or other mechanical devices that can induce air circulation could be employed to exhaust excessive moisture (Becker 127). In addition to expending humidity, these gadgets also eliminate heat. As a result, a humidistat or timer should be put in place to control their operating period to ensure that the office space does not get extremely cold (Becker 127). As well, a more passive and temporary method would be to ensure that all the operable windows are kept open during the office hours and when it is not unusually cold to allow for cross ventilation (McNeil 2015). Using air to air exchanger is yet another expensive method of condensation reduction through the removal of dampness from the interior space (GreatDay 2018). The gadget extracts the humid air from the inside of the building and replaces it with fresh and less moist outdoor air.
Thirdly, the client can consider using moisture eliminators such as DampRids (GreatDay 2018). These products help in pulling out the excessive vapour present in the muggy air. They are basically crystals of anhydrous calcium chloride and become active only when the humidity levels are higher than usual (McNeil 2015). Also, a less expensive weatherstripping technique could be tried out. It involves the use of a suitable material to fill in the gaps that allow for air leakages on windows (Becker 127). In such as case, it has to be first determined using the appropriate measurement techniques that indeed, the external humid air finds its way into the interior office spaces through these gaps and cracks located on the windows (Becker 127). Especially during winters, moist draughts usually find their way into buildings raising the relative humidity of the air and subsequently increasing the condensation levels. For stationary window components, silicone or caulk would be the most appropriate material. Further, the caulk helps replace or repair the putty that was initially used around the glazing (Becker 127). Other movable windows that are either double-hung or slider-casement could have their sashes wrapped precisely using adhesives such as foam tape, felt, V-strip tension seal, or magnetic weatherstripping (Becker 127).
The fourth approach would be to enhance the thermal qualities of the windows where condensation occurs. To realize such results, insulated glazing could be employed to assist in retaining the indoor temperatures (Branz 2017). This method uses the same principle as installing storm windows or double glazing. The second layer of glass is useful in the sense that it keeps its internal surface warmer than the area outside the building (Becker 127). Therefore, the probability of condensation forming on more heated windows is considerably reduced. These are mounted temporarily or permanently either to the inside or outside of the whole glazed window surface. They provide an efficient energy-saving solution through thermal insulation and could be made of flexible sheets and rigid panels of plastic or glass (Becker 127).
Lastly, the specification of different types of window frames such as those with an in-built system of passive ventilation can help reduce condensation to a great extent. These frames could have vents which allow for continuous air circulation within the office space while still maintaining the security of the users. According to Branz, the recommended vent size per window frame should be about 600mm. Additionally, using aluminum frames that are thermally broken could turn out to be 60% more efficient in minimizing condensation compared to other components (Branz 2017). This is because they have a spacer located between the outer and inner metal frame parts which, in turn, increases its degree of thermal performance. Other methods could be using timber, uPVC, and composite aluminum window frames that are thermally efficient (McNeil 2015). Also, fiberglass could be used in place of the glazed windows due to its desirable thermal properties in both extreme cold and hot climates. Unlike glass, it does not allow frost to settle on its surface or become slippery even when temperatures go beyond zero (Branz 2017).
In conclusion, condensation in the large office space occurs when the high humidity from the steam heating and chilling systems comes into contact with the cold glazed windows. For that reason, the problem of vapor condensation can either be solved by controlling the internal humidity or by enhancing the thermal properties of the windows, for instance, through double glazing. The indoor moisture can be minimized by regulating the AHU unit which is the primary sources of water vapor or through ventilation. If these techniques do not work, then heating systems should be employed to raise the interior temperatures, but only as a last resort.
Works Cited:
Alberta Infrastructure. Indoor Air Quality Tool Kit. Technical Services Branch (2006), p. 27.
Becker, Franklin. Department of design and environmental analysis Cornell University. Building Evaluation (2013). P. 127.
Branz. Passive Design: Humidity and condensation. (2017). Extracted from: http://www.level.org.nz/passive-design/controlling-indoor-air-quality/humidity-and-condensation/
GreatDay Improvements. Window condensation solutions. Stanek Windows (2018). Extracted from: https://www.stanekwindows.com/17-window-condensation-solutions.aspx
McNeil, Stephen. Combating internal moisture. Branz (2015). Extracted from: https://www.buildmagazine.org.nz/articles/show/combating-internal-moisture/
