A clothes line or washing line is any type of rope, cord, or twine that has been stretched between two points (e.g. two sticks), outside or indoors, above the level of the ground. Clothing that has recently been washed is hung along the line to dry, using clothes pegs or clothes pins. Washing lines are attached either from a post or a wall, and are frequently located in back gardens, or on balconies. Longer washing lines often have props holding up sections in the middle due to the weight of the clothing.
More elaborate rotary washing lines save space and are typically retractable and square or triangular in shape, with multiple lines being used (such as the Hills Hoist from Australia). Some can be folded up when not in use (although there is a hazard of getting fingers caught, so there is usually a safety button).
In Scotland, many tenement buildings have a drying green which is a communal area predominantly used for clothes lines - it may also be used as a recreational space.
Zero greenhouse gas emissions per load (2 kg of greenhouse gas emissions from the average mechanical clothes dryer per load)
Laundry smells "clothes-line fresh" without using chemicals
Less fabric wear and tear
Laundry items do not shrink (hot air from a mechanical clothes dryer may shrink items)
No static cling
Laundry items stay softer to the touch (mechanical clothes dryers tend to remove short, soft, fine fibers), and may be less wrinkled
Avoids the potential of airborne lint and reduced air quality
Eliminates the noise from a mechanical clothes dryer
Does not vent to the outside and waste the large volume of conditioned (heated or cooled) indoor air that a mechanical dryer's blower does.
For a simple line drying arrangement (rope and clothes pins) the repair and replacement costs are about $20.00 per 1,000 loads of laundry or 2¢ per load. For non-commercial mechanical clothes drying the repair and replacement costs (including labor expenses) are about $200.00 per 1,000 loads of laundry or 20¢ per load.
Laundry may be dried indoors rather than outdoors for a variety of reasons including:
lack of space for a line
to raise the humidity level indoors, and lower the air temperature indoors
convenience, or preserve privacy
Several types of devices are available for indoor drying. A drying rack or clotheshorse can help save space in an apartment or clothes lines can be strung in the basement during the winter. Small loads can simply be draped over furniture or a shower curtain pole. The drying time indoors will typically be longer than outdoor drying because of the lack of direct solar radiation and the convective assistance of the wind.
The evaporation of the moisture from the clothes will cool the indoor air and increase the humidity level, which may or may not be desirable. In cold, dry weather, moderate increases in humidity make most people feel more comfortable. In warm weather, increased humidity makes most people feel even hotter. Increased humidity can also increase growth of fungi, which can cause health problems.
An average-sized wash load will convert approximately 3165 joule of ambient heat into latent heat that is stored in the evaporated water.
To determine how much heat has been converted in drying a load of laundry, weigh the clothes when they are wet and then again after the clothes have dried.
The difference is the weight of the water that was evaporated from them. Multiply that weight in kg by 2,257, which is the heat of vaporization per kilogram, to obtain the number of Kjoules that went into evaporating the water, or multiply by 625 to get watt-hours.
(Note: If the moisture later condenses inside the house, the latent heat will be converted back into ambient heat which could increase the temperature of the air in the room slightly.)
To obtain a good approximation of the effect this would have in a particular situation, the process can be traced on a psychrometric chart.