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Thermal insulation
Published in Derek Worthing, Nigel Dann, Roger Heath, of Houses, 2021
Derek Worthing, Nigel Dann, Roger Heath
Condensation is caused when moisture-laden air comes into contact with a cold surface and the moisture that the air is carrying as vapour is deposited as water on that surface. Air can hold varying amounts of moisture, depending on its temperature. The higher the air temperature the more moisture it can hold. Moisture in the air occurs due to natural conditions but is added to in a building by people breathing, by activities such as washing and cooking and as a by-product of burning substances such as paraffin or bottled gas in heaters. The amount of water generated in an ‘average’ family house can be as high as 14 litres a day. The problem is aggravated if high amounts are generated over a short period of time from cooking, drying clothes, etc., especially if this happens in one particular room. Kitchens and bathrooms are, therefore, the rooms most likely to suffer from condensation.
House As a System
Published in Stan Harbuck, Donna Harbuck, Residential Energy Auditing and Improvement, 2021
Condensation is water vapor that has changed to liquid water. Typically, this occurs when air is cooled down. The higher the humidity, the greater the risk of condensation when the air is cooled. Evaporation is the opposite of condensation and involves the transformation of liquid water into water vapor. Absolute humidity tells what the water vapor to air volume ratio is in a given sample of air. The more moisture in the air, the higher the absolute humidity. This is sometimes referred to as the vapor pressure.
Guidance on the common damp problems
Published in Ralph Burkinshaw, How to Investigate Damp, 2020
Condensation occurs when air containing moisture cools down to its dew point with vapour pressure constant. Inside properties, the cooling is very often caused by a cold surface, to release water from the air which collects in droplets – the condensate.
Has a singular focus of building regulations created unhealthy homes?
Published in Architectural Science Review, 2020
Shruti Nath, Mark Dewsbury, Jeroen Douwes
Within the external envelope, a significant element that is not well understood within the Australian regulatory framework and the design and construction professions is thermal bridging (Dewsbury et al. 2018). The thermal bridging can be caused by solid elements, like the timber or steel structure, or could be caused by the leakage of cool air inward or warm air outward. When warm and water vapour laden air comes into contact with the cool surface or cool air, condensation occurs. The Passive house standard requires 0.6 Air Changes per Hour when a 50 Pascal pressure difference is applied between the interior and exterior environments (ACH50). Ambrose and Syme (2017) measured ACH50 values up to 39.0 in new homes in Sydney and Perth, which would provide significant thermal bridging and condensation risk within the built fabric.
The role of structure cooling to reduce the effect of urban heat island in Mumbai
Published in Advances in Building Energy Research, 2019
Aparna Dwivedi, M. V. Khire, B. K. Mohan, Surendra Shah
Use of radiant slab cooling in hot humid climates requires some special measures. The supply air requires dehumidification to prevent condensation. The chilled water supplied to the cooling coils must be reduced to about 6°C to dehumidify supply air or desiccant cooling equipment may be applied.The building envelope must be airtight. The infiltration rate through building envelope has to be kept low. Natural ventilation without combined control is problematic for radiant slab cooling in humid climates due to condensation risk.Heat gains through the building envelope, especially gains due to solar radiation through glazing, must be kept low so that the temperature of chilled water supplied to the radiant slab can be increased, which reduces the possibility of condensation. Radiant cooling with dedicated outdoor air system may have better performance than conventional systems in hot and humid climates.
Investigation of airflow onto uncooled and cooled perpendicular substrates for bioaerosol sampling
Published in Aerosol Science and Technology, 2023
Zhixiong Song, Hassan Ali Abid, Eric Shen Lin, Jian Wern Ong, Md. Hemayet Uddin, Kenneth Margo, Oi Wah Liew, Tuck Wah Ng
Condensation is a mass and heat transfer process through the vapor–liquid interface. The ability to quantify the degree of mass transfer through vapor–liquid interface provides insights into the aerosol impaction process. Experimentation was conducted to collect water from the center and edge regions over a period of 12 min. Based on these, the mass transfer coefficient can be determined using where is the rate of water harvested, A the area, and ρe (=0.6 kg/m3) and ρc (=0.006 kg/m3) are the saturated water vapor density at evaporation and condensation, respectively.