regulate+humidity

Sources of Excessive Moisture in Buildings and their Reduction
Excessive moisture in buildings can result from a number of causes: Rainwater Leaks: The control of rainwater leaks has been the subject of good building practices for as long as human habitations have been built. Even infrequent but serious leaks during heavy storms can lead to mold infestation, are annoying, and can cause serious damage to buildings and their contents. Less severe but more frequent leaks and slow but persistent leaks can cause equally serious damage. Leakage of Moist Air: Warm and moist indoor air condenses on cold surfaces and interstitial planes inside constructions. This moisture can be stored harmlessly within construction materials or can cause mold growth and deterioration. Excessive moisture content in wood can cause mold growth and dry rot on wood, rust on unprotected steel, and loss of insulating value in thermal insulations. Duffusion of Moisture through Walls, Roofs, and Floors: Diffusion, as a result of differing vapor pressures across walls or roofs moves moisture through building materials. Materials with low permeancies allow little vapor transmission; materials with high permeancies allow more moisture transmission. Convention calls materials with a Permeance of 1 perm (in SI units, 57 nanogramsof water per second for each square meter of area) "vapor retarders." Note that the diffusion is dependent on vapor pressure resulting from differences in temperature and relative humidity of the air on the two sides of the wall or of individual materials. Groundwater Intrusion: Intrusion of groundwater into basements and crawl spaces is common. This can result from a high water table or from rainwater runoff soaking into the ground at the basement/crawl space walls. Because most basements and crawl spaces are connected through cracks, pipe chases, and stairways to the rest of the building, moist air from wet basements and crawl spaces will find their way into occupied and other spaces above. Leaking or Burst Water Pipes: The prevention and repair of burst or leaking pipes is the responsibility of plumbers. Except for old steel and iron pipes and frozen pipes, there should be little concern for this issue. However, in some geographic areas, recently installed copper pipes have been found to develop small pinhole penetrations leading to slow but constant leaks. In general, correctly installed pipes made of quality materials should not be a problem for many years after installation. Indoor Moisture Sources: Human occupancy: breathing, perspiration, cooking, bathing, and clothing washing can add significant amounts of moisture to buildings. Kitchens and bathrooms should be independently vented and washers need to be vented outdoors. Open sumps, aquariums, indoor swimming pools, and hot tubs, as well as excessive indoor plants can increase indoor humidity beyond the recommended 30 to 50 percent. Moisture sources should, where possible, be covered by tight lids when not in use. Construction Moisture: Wet construction materials, such as in-situ cast concrete and lumber stored unprotected outdoors prior to installation can increase indoor humidity significantly during the first one to two years of occupancy.
 * Rainwater leaks through roofs and walls
 * Leakage of moist air
 * Diffusion of moisture through walls, roofs, and floors
 * Groundwater intrusion into basements and crawl spaces through walls and floors
 * Leaking or burst water pipes
 * Indoor moisture sources and
 * Construction moisture.

[] - How to measure humidity in the home.


 * One person’s breathing produces 1/4 cup of water per hour.
 * Cooking for a family of four produces approximately five pints of water in 24 hours.
 * Showering puts 1/2 pint of water into the air.
 * Bathing puts 1/8 pint of water into the air.

What are the correct amounts of relative humidity for a correct environment?
For a pleasant working environment, it is important to make sure relative humidity does not fall below 40%. When relative humidity is less than 40%, the risk of disease is increased. Generally, it can be stated that symptoms that are caused by dry air vary, but three main factors can be distinguished: static electricity, moisture stability and health effects.

Static electricity
Dry air can cause static electricity in an environment. Static electricity can be diminished by increasing the relative humidity of air. Machines in a machine park give off static electricity as a result of friction. When there are more machines present that are active during a longer period of time, more friction will take place and the risk of static electricity increases. This mainly occurs at dry machine elements. In computer rooms, there is also a static electricity risk. Most static electricity is caused at a relative humidity of between 30 and 35%.

Moisture stability
Moisture stability means the ability of a material or product to maintain a certain level of moisture, despite fluctuations of relative humidity in its environment. Most materials give off or take up moist. This can cause damage to a material or product. In many sectors –such as vegetables, fruits, flowers and granes- this process is irreversible. When relative humidity is too high, this can also cause problems for antiques, paintings, books, papers, etc. Most damage to older products is caused by air humidity fluctuation.

Health effects
As temperatures increase, relative humidity decreases. Dry air can cause health effects, such as dry nose and throat. This causes a higher susceptivity to pathogens such as viruses. When it is cold, a higher air humidity makes people believe it is warm. This causes the heater to be on less often. It appears that the climate is detrimental for bacterial growth when relative humidity is between 40 and 60%. Viruses can survive least at a relative humidity of between 47 and 70%. For people, relative humidity is most pleasant between 40 and 60%. For people that suffer from allergies and astma, relative humidity must be between 45 and 55%. High relative humidity can cause constriction.

[] - study on effects of humidity on sick building syndrome [] - British standards for internal air quality [] - problems & solutions re humidity

** OCCUPANT COMFORT ZONE(S) **

Comfort Zones. Because of high energy costs, the DPW&T Building Services Division has established **temperature** Comfort Zones for heating and cooling. In the winter, the set point for heating is **20.5** degrees C (the standard acceptable temperature range is between 20 to 22 degrees). In the summer, the set point is **24.5** degrees (the standard acceptable temperature range is between 24 to 25.5 degrees). However, for facilities that provide services to seniors, the year-round set point is **24.5** degrees.

Heating and Cooling Seasons. The typical cooling season begins on **October 1** **5** and ends **April 1** **5** each year. The heating system is deferred as long as is practical after **April** **15** and is terminated as soon as possible prior to **October** **15**. In addition to thermal comfort, the **relative humidity**, for most applications, should be between 40% and 70%, with a 65% threshold to help prevent the growth of mold. The relative humidity Comfort Zone should not be lower than about **30%** (to prevent occupant discomforts such as dry eyes and throats, shrinking of wood flooring, and static electricity problems on carpet, and possible sick building syndrome symptoms) or higher than about **60%** in the **//center of the room//.** The 60% level is intended to keep the relative humidity from exceeding 70% at surfaces, such as walls and floors.

** Relative Humidity ** **.** The relative humidity at surfaces is typically higher than it is at the center of a room. When the relative humidity at surfaces is above 70%, mold growth can occur. To control microorganisms, it is best to keep relative humidity below 60% to control mold and 50% to control dust mites. The accuracy of the standard humidity range is 3/5th% to 3% (say 2%) over the established comfort zone. For libraries and archival materials, a stable temperature of no higher than 70 degrees and a relative humidity of between 30% and 60% is recommended.

Desirable relative humidity and temperature for each activity
Below, a table is shown that outlines ideal temperatures and relative humidity for each sector in a given situation. This table is derived from JDK air-handling.
 * == **Activity** == || == **Temperature (°C)** == || == **Relative humidity (%)** == || == **Activity** == || == **Temperature (°C)** == || == **Relative humidity (%)** == ||
 * **//Bakery//** ||  ||   || **//Leather//** || 1 ||   ||
 * //Biscuits and cookies// || //16-18// || //50// || //Storage room// || //10-16// || //40-60// ||
 * //Fermentation// || //24-27// || //70-75// ||  ||   ||   ||
 * //Flour storage room// || //18-27// || //50-65// || **//Libraries//** //**and Museums**// || //21-27// || //40-50// ||
 * //Bread cooler// || //21// || //60-70// ||  ||   ||   ||
 * //Confectionery// || //24-27// || //65-70// || **//Paper products//** ||  ||   ||
 * //Mixing bread dough// || //24-27// || //40-50// || //Binding// || //21// || //50-65// ||
 * //Yeast storage room// || //0-7// || //60-75// || //Wrinkling// || //24// || //60-65// ||
 * ||  ||   || //Printing office// || //24-27// || //45-55// ||
 * **//Grains//** ||  ||   || //Storage room// || //24-27// || //40-60// ||
 * //Packing// || //24-27// || //45-50// ||  ||   ||   ||
 * ||  ||   || **//Textile//** ||   ||   ||
 * **//Confectionery//** ||  ||   || //Cotton processing// || //24-27// || 50-55 ||
 * //Chocolate sales// || //17-18// || //50-65// || //Cotton spinning// || //16-27// || 50-70 ||
 * //Storage room// || //16-20// || //50-65// || //Artificial silk spinning// || //20-24// || //85// ||
 * ||  ||   || //Cotton weaving// || //27// || //56-60// ||
 * **//Food industries//** ||  ||   || //Wire torsie artificial silk// || //21// || //60// ||
 * Apple storage room || //-1// || //75-85// || //Silk processing// || //24-27// || //65-70// ||
 * //Banana ripening// || //20// || //90-95// || //Wool refining// || //27-29// || //65-70// ||
 * //Banana storage room// || //16// || //85-90// || //Wool spinning// || //27-29// || //50-60// ||
 * //Citrus fruits storage room// || //16// || //85// || //Wool weaving// || //27-29// || //60// ||
 * //Eggs storage room// || //2-13// || //75-80// ||  ||   ||   ||
 * //Grains storage room// || //16// || //30-45// ||  ||   ||   ||
 * //Mushrooms storage room// || //0-2// || //80-85// || **//Tobacco//** ||  ||   ||
 * //Potatos storage room// || //4-16// || //85-90// || //Cigars and cigarettes// || //21// || //55-65// ||
 * //Sugar// || //27// || //30// || //Processing and storage// || //24// || //70-75// ||
 * //Tomatoes storage room// || //1// || //85// || //Packing// || //32// || //88-95// ||
 * //Tomatoes riping room// || //21// || //85// ||  ||   ||   ||
 * ||  ||   || **//Wood processing//** ||   ||   ||
 * **//Hospitals//** ||  ||   || //End products// || //18-21// || //35-40// ||
 * //Children’s ward// || //24// || //50-65// || //Fixing// || //24-24// || //40-50// ||
 * //Operation room// || //24// || //55// || //Processing// || //18-24// || //35-40// ||
 * //Hospital rooms// || //24// || //40-50// ||  ||   ||   ||
 * ||  ||   || **//Conservatories//** || //27// || //70-80// ||
 * **//Painting companies//** || //22-24// || //40-50// ||  ||   ||   ||

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