The four approaches for passive solar heating in skin-load dominated buildings.
The Tierra Concrete homes are updated by the U.S. Department of Energy Federal Energy Management Program.
There are several design approaches called passive solar design.These strategies can contribute to the heating, cooling, and daylighting of nearly any building.barracks to large maintenance facilities are some of the types of buildings that benefit from the application of passive solar heating.
Passive solar heating systems don't have a high initial cost or long-term payback period, both of which are common with active systems.Increased user comfort is one of the benefits of passive solar heating.Passive solar buildings are bright and sunny if they are properly designed.The result is a higher degree of temperature stability and thermal comfort.Passive solar buildings can contribute to increased satisfaction and user productivity by providing a delightful place to live and work.Passive solar design does not cause greenhouse gases.
There are a few things to consider when designing a passive solar design.To achieve the highest efficiency, the system needs to be exposed to the sun.The system can overload if the intensity of sunlight is intermittent.Passive solar design costs less than conventional building design and saves money over the long term, thanks to the help of experienced passive solar designer architects and builders.
During the initial design, it is best to include passive solar heating.The whole building approach looks at it in the context of building envelope design, daylighting, and heating and cooling systems.Daylighting and views to the outside are provided by passive solar heating strategies.The effectiveness of passive solar heating can be determined by window design.Additional south-facing windows, additional thermal mass, and roof overhangs are passive solar features that can easily pay for themselves.When the annual energy and maintenance costs are taken into account, passive solar buildings are often less expensive.
Specific details for Federal agencies regarding passive solar heating technologies as part of a new construction project or major renovation are provided in this overview.
Passive solar heating systems use the building components to collect, store, and distribute solar heat gains to reduce the demand for space heating.A passive solar system does not require the use of mechanical equipment because the heat flow is by natural means, such as radiation, and the thermal storage is in the structure itself.
The components that make up a passive solar heating system must work together in order to be successful.
In a passive solar heating system, the collector is a large glass area through which sunlight enters the building.During the heating season, the building should not be shaded by other buildings or trees from 9 a.m. to 3 pm.
The absorber is the hard, dark surface of the storage element.The surface could be a masonry wall, floor, partition, or water container.Sunlight is absorbed as heat when it hits the surface.
The thermal mass is made up of materials.The absorber is an exposed surface, whereas the thermal mass is the material below or behind that surface.
The method by which solar heat circulates from the collection to different areas of the building is called distribution.The three natural heat transfer modes will only be used in a strictly passive design.Fans, ducts, and blowers can help with the distribution of heat through the building.
In order to help control under- and overheating of a passive solar heating system, there are elements such as roof overhangs, which can be used to shade the area during the summer months, and electronic sensor devices, like a differential thermostat that signals a fan to turn on.
Passive solar buildings block out the sun during hot summer days and let the heat in during the winter.Passive solar design elements such as shading, implementing large south-facing windows, and building materials that absorb and slowly release the sun's heat can be achieved.
Incorporating shading concepts into your landscape design can help reduce the solar heat gain in the summer.The leaves of trees and bushes located to the south of the building can help block out the sun in the summer.The leaves of these trees are lost in the winter, allowing for an increase in solar heat gain.The shade can be provided by incorporating overhangs, awnings, shutters and trellises into the building design.
A climbing vine can shade a home and allow air circulation.
Concrete or stone floor slabs have high specific heat capacities and high density.It is placed within a building that is exposed to winter sunlight and insulated from heat loss.During the night, the material is warmed by the sun and released into the interior.
Passive solar design relies on the integration of a building's architecture, materials selection, and mechanical systems to reduce heating and cooling loads.It is important to consider local climate conditions, such as temperature, solar radiation, and wind, when creating structures that can be powered with renewable energy sources.
Large south-facing windows are used in climates that are appropriate for passive solar heating because they have the most sun exposure.Although passive solar heating systems do not require mechanical equipment for operation, fans or blowers may be used to assist the natural flow of thermal energy.The passive systems are referred to as hybrid heating systems.
Basic concepts are incorporated into the architectural design of the building.A glazed south-facing wall, a thermal storage media exposed to the solar radiation, and other shading devices are included in this.
It is necessary to have adequate thermal mass in buildings to achieve a high percentage of passive solar heating.There are specific guidelines for this.
Climate will affect insulation values, shading, and mass.Higher solar savings contributions will require more mass.The relationship between glass area and mass is not linear.A doubling of glass area may require a tripling of thermal mass.
There are two main uses for passive solar heating, skin-load dominated buildings in cold and warm climates.Solar energy can be used to provide space heating for small buildings in cold climates.In warm climates, responsible passive solar design is more likely to emphasize cooling avoidance using shading devices, high performance glazing, and daylighting.
The influence of the exterior climate on a building's envelope is what determines energy consumption in a skin-load dominated structure.barracks and other low-rise housing, small warehouses, or small retail facilities are examples of skin-load dominated buildings.
Most of the energy used in educational facilities, offices, or large retail complexes is consumed to provide interior lighting and cooling to counteract the heat given off by people, plug-loads, and other internal sources.The buildings need cooling year-round.In the summer, less solar radiation enters a well-shaded south window than a similarly shaded window on the north, east, or west side of the building.
There are four generic passive solar heating approaches for skin-load dominated buildings.
Sun-tempering can be achieved with modest increases in south-facing windows.A tract builder's house typically has one quarter of its windows on each facade with a south glass equal to 3% of the total floor area.Depending on the climate, a sun-tempered house or barracks could increase this percentage to between 5% and 7%.The "free mass" of gypsum wallboard and furnishings is enough to store the additional solar heat.
Direct gain is the most basic form of passive solar heating.Sunlight enters the space through the south-facing window and is stored in a thermal mass in the floor or interior walls.The total direct gain glass should not be more than 12% of the house's floor area.Problems with glare or fading of fabrics are likely to occur, and it becomes more difficult to provide enough thermal mass for year-round comfort.
An indirect gain passive solar heating system is a south-facing glazed wall, usually built of heavy masonry, but sometimes using containers of water or phase change materials.During the day, the sun is absorbed into the wall.As it cools gradually during the night, it releases its stored heat into the space.
Sunspace is an area that can be closed off from the rest of the building because of passive heating.During the day, the doors and windows between the sunspace and the building are open, and then closed at night, allowing the temperature to drop.It is possible to move heat into adjacent rooms with small circulating fans.
The Arizona Solar Center has a manual on passive solar design.External concrete walls that are insulated on the outside are now available.The concrete should be exposed on the inside.
When appropriate, passive solar heating strategies should only be used.Smaller buildings with the envelope design have a better use for passive solar heating.The space is not already heated by busy people, lights, computers and other internal heat gain.Strategies, such as trombe walls, exist to mitigate unwanted glare and excessive heat gain, but care must be taken when introducing solar heat into workspace.The flexibility to move out of the sun is a result of passive solar heating being used on circulation spaces such as lobbies and atria, hallways, break rooms, and other types of spaces with low internal heat gain.
The primary types of buildings that can benefit the most from the application of passive solar heating principles are:
Modest levels of passive solar heating, also called sun-tempering, can reduce building auxiliary heating requirements from 5% to 25% at little or no initial cost and should be implemented for all small buildings in cold climates.Passive solar heated buildings can reduce heating energy use by 25% to 75% compared to a typical structure while remaining cost-effective on a life-cycle basis.Many small buildings in cold climates should consider this approach.
Passive solar design costs less than conventional building design and saves money over the long term, thanks to the help of experienced solar designer architects and builders.In areas where experienced solar architects and builders are not available, construction costs can run higher than for conventional buildings, and mistakes can be made in the choice of building materials.Passive solar homes are often built with glass that doesn't accept solar energy.This is a costly mistake.On which side of the building the glass is installed depends on the climate.
Daylighting can increase energy use in a building by adding to its air-conditioning load.
In climates with clear skies during the winter heating season and where alternative heating sources are less expensive, passive solar heating is the most economical option.
A good passive solar site will allow its solar surfaces to face true south with a minimal amount of shading in the solar access zone.The area to the south must be clear of obstructions that could block the sun from reaching them in order to ensure their performance.Between 9 a.m. and 3 pm, there should be no significant obstructions.
To avoid shading the building in winter, obstructions to the south need to be at least 1.7 times their height away from the surface.Obstructions located east or west of the 45 lines need to be at least 3.5 times their height away from the building to avoid shading.In winter, the sun is lower in the sky and casts longer shadows.Even if the site is unshaded in the summer, it may not be that way in winter.
The following recommendations should be followed when using passive solar heating technology.
There is very little need for maintenance or attention beyond what is required for the building envelope in general, since passive solar heating is implemented during a building's initial construction.Maintenance must make sure that areas designed to gain solar heat are not shaded by landscaping or other obstructions.
Evaluations of the performance of passive solar heated buildings can be found through the DOE's Exemplary Building Program.The National Renewable Energy Laboratory has a description of the projects for building energy analysis.
There is an ongoing program of case study publication in Solar Today magazine.
To analyze the performance of large, internal-load dominated buildings, see DOE-2.The use of a more powerful computer program is required for the solar heating performance of larger buildings.Multi-zone programs developed by the government are recommended.