EFFECTS OF HUMIDITY

PREPARED BY, SHRADDHA PALANDE

INTRODUCTION

• Humidity is a term for the amount of water vapor in the air.

CAUSES OF HUMIDITY

• Humidity in buildings has a variety of causes.• Following are the causes of humidity:

• Building related causes - Rising dampness, leakage, porous walls

• Drying and washing • Kettles• Baths and showers• Wet clothes• Ambient high humidity outside

EFFECTS OF HUMIDITY

• Humidity is noticeable by its symptoms.• Following are the effects of humidity:

• Damp or wet walls• Mold• Peeling and blistering wallpaper• Breakdown of plasterwork• Mildew• Doors and windows does not fit properly• Swelling wooden furniture• Health deterioration (coughs, asthma, etc. triggered by mites and mold spores)• Clothing damaged by mold• Window condensation

Excessive moisture in buildings can result from a number of causes:

• 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• Construction moisture

• 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 which can cause serious damage to buildings

• 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.

• Diffusion of Moisture through Walls, Roofs, and Floors: Diffusion, as a result of differing vapor pressures across walls or roofs moves moisture through building 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.

• 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.

EFFECTS OF HUMIDITY:

IN HUMID AREAS:1. A person tends to perspire more easily, especially under

physical exertion. This results in a sticky feeling on the skin. Arising from heavy perspiration, it is necessary to drink water often to make up for the loss so as to replenish the body.

2. After washing, wet clothings will take a longer time to dry, although the presence of winds help.

3. Metal objects tend to rust faster as the moisture in the air facilitates the process of oxidation.

4. When kept in the cupboard for a long time, books and magazines get affected by mildew, while food, clothing’s and leather products turn moldy.

EFFECTS OF HUMIDITY:ON ARID REGIONS:1. Even as a person exerts himself/herself, the perspiration coming out of

the person's sweat pores evaporates into the air quickly. So, the skin feels dry.

2. When in the open, the lack of natural moisture in the air causes the external layer of the skin (the epidermis) to dry up quickly, resulting in cracked lips and peeling skin. It is also important to keep the body hydrated by drinking sufficient amounts of water. When indoors, humidifiers should be used to maintain a comfortable level of humidity. Another simple method is to leave bowls of water in the different rooms and let natural evaporation keep up the humidity level.

3. Due to the lack of humidity, which is often accompanied by the lack of wind, the air is more dusty. If there are a lot of pollutants and small particles in the air, smog is formed, which is bad for health.

INDOOR HUMIDITY EFFECT

• In cold climates, the maximum sustainable indoor humidity depends on the thermal and moisture characteristics of the external envelope and the outdoor temperature. When indoor humidity exceeds the tolerance level of the walls and roof, disastrous consequences may occur.

• The frequency of moisture problems was directly related to the occupant density. High occupant density tends to result in large amounts of moisture released, thus high indoor humidity.

• In all the coastal regions; buildings struggle with far greater levels of moisture in the air. This moisture laden air enters homes and businesses causing our HVAC systems to run much longer. The increased run times cause our utility bills to also increase significantly.

• Our air conditioning and heating systems not only keep us cool in the summer and warm in the winter; they also dehumidify our indoor air. Lower levels of moisture in the air, greatly improves comfort levels inside a building. You see our skin feels too hot or cold if temperatures are too high or low and higher humidity levels magnify our level of discomfort.

BENEFITS OF DEHUMIDIFIERS

Dehumidifiers should be used to reduce humidity.• The benefits of reducing the humidity at home or

work place are as follows:• Protection of building from damp and mold • Protection of contents of building from mold and

damp damage• Protection of items in long term storage• Reduction in condensation• Quicker drying