{"id":22593,"key":"Passive_solar_design","title":"Passive solar design","latest":{"id":1274505,"timestamp":"2026-09-16T16:58:36Z"},"content_model":"wikitext","license":{"url":"https://www.appropedia.org/Appropedia:Copyrights","title":"CC-BY-SA-4.0"},"source":"{{Topic notice}}\n\n[[File:Building-a-passive-solar-greenhouse.jpg|thumb]]\n\n'''Passive solar design''' is the harnessing or directing of solar energy through non-mechanical, non-electrical means. It is a key principle of [[green building]], often applied in designing buildings for maximum solar heating during cold winter months and maximum protection from the sun's heat during hot summer months. Passive solar is distinguished from active solar by the lack of operable devices.\n\nThere are 6 main types of passive solar design.<ref name=\"Haggard\">Passive Solar Architecture Pocket Reference. Ken Haggard, David A. Bainbridge, Rachel Aljilani. International Solar Energy Society / Routledge, 2016</ref> These can be considered in 3 generic categories in terms of the relationship between the thermal collector (or dissipator) and the interior space of the structure.<ref name=\"bainbridge2011\">Passive Solar Architecture: Heating, Cooling, Ventilation, Daylighting and More Using Natural Flows. D Bainbridge, K Haggard. Chelsea Green Publishing, 2011</ref> These categories are [[Passive solar design#Direct gain|direct gain]], [[Passive solar design#Indirect gain|indirect gain]] and [[Passive solar design#Isolated systems|isolated systems]]. Within each category, there are 2 distinct approaches.<ref name=\"bainbridge2011\" />\n\n== Direct gain ==\n\nDirect gain is a type of [[passive solar]] heating system that uses direct solar radiation to heat a building. In these systems, thermal transfer occurs within the building interior and it may either be ''distrubeted throughout the building'' (e.g. the floors and the pole facing walls), or ''mass may be concentrated''..<ref name=\"bainbridge2011\" />\n\nBuildings using a direct gain system use large, south-facing windows to admit sunlight. However, using a direct gain system requires that a structure uses [[thermal storage]] material to absorb the [[radiation]]. A failure to do so will result in inside temperatures rising to more than 90deg F.\n\n== Indirect gain ==\n\nIn '''indirect gain''' systems, thermal transfer takes place at the building envelope.<ref name=\"bainbridge2011\" />The 2 types of indirect gain system are the ''thermal wall or trombe wall'' and the ''roof pond''.<ref name=\"bainbridge2011\" />\n\n=== Trombe wall ===\n\n{{Excerpt|Trombe wall}}\n\n== Isolated systems ==\n\nThe 2 approaches of isolated systems are the ''sunspace'' and the ''thermosyphon''.<ref name=\"bainbridge2011\" />\n\n=== Thermosyphon ===\n\n{{Excerpt|Thermosyphon}}\n\n== Key design techniques ==\n\nKey building design techniques include:\n\n* Planting deciduous trees or [[trellises]] covered in deciduous or annual vines. This may be as a fence or as a shade roof, and provides shade in summer and light and warmth in winter.\n* Designing and building components with consideration for the seasonal change in the sun's position in the sky, and the influence this will have on the angle and intensity of light hitting the structure. Examples of this include:\n** Broad eaves, which block sunlight from entering windows during the summer, but allows it to enter during the winter when the sun is lower in the sky.\n** Shade walls (less common): A wall or fence beyond the limits of the house, to provide shade. The wall runs east-west, on the east and/or west side of the house, and is on the north side of the house in the northern hemisphere, and on the south side in the southern hemisphere (i.e., away from the equator). The angle and placement are calculated to shield the house from early morning or late afternoon sun in summer but not in winter. However, this requires significant resources and, unless there are other reasons for a wall, it is generally better to use other methods, such as deciduous trees, or an awning, especially where there are large windows.\n* [[Thermal mass]]: A critical component of any passive solar design. Its purpose is to absorb and re-radiate heat energy. This has the effect of averaging out the daily extremes of high and low temperature. Thermal mass generally falls into two categories, passive and active. Passive thermal mass heat-storage systems include:\n** Thick masonry walls and floors\n** Phase-change materials: These materials change phase (typically from solid to liquid) when heated, storing a great deal of heat energy without a corresponding change in temperature. Examples include various high-tech concrete additives and also natural resins, such as those found in Southern Yellow Pine.\n** Large liquid storage tanks inside the space to be heated (or cooled)\n* Pipes to transfer heat between air and the thermal mass (e.g., in the ground under the house, either with natural convection or with a quiet low-power fan)\n* [[White roofs]]\n** Dark roofs absorb large amounts of solar energy, which transfers into the building. This increase in absorbed heat requires increased electrical energy to remove and cool buildings, homes, and workplaces and maintain a comfortable environment. Dark colors also radiate heat more easily in cold conditions, meaning greater heat loss from buildings and higher heating costs.\n** White surfaces have an increased albedo or \"whiteness,\" which is the reflectivity of a surface. If a roof is more reflective less energy will be absorbed and transferred to the building.\n* Solar closets\n** A shallow glass-fronted closet, lined with dark material, becomes very hot when exposed to the sun. One-way valves (which might be as simple as plastic sheet over wire mesh) allow cool air to enter at the bottom and hot air to exit at the top. They can be used for heating hot water, as well as for space heating.\n* When these measures are appropriately utilized and combined the energy efficiency of a building can be much higher than with more conventional design measures.\n\n== Passive solar vs passive house ==\n\nThe terms passive solar design and [[passive house]] are often confused. The two terms refer to [[green building]] techniques and are closely related.<ref name=\"thorpe2018\">Passive Solar Architecture Pocket Reference. D Thorpe. Earthscan from Routledge, 2018</ref>\n\nPassive solar design is about making best use of available natural light and heat. Heat from the sun is collected (if heating is desired, i.e. in a cool climate). A major part of passive solar design is careful orientation with respect to the sun.<ref name=\"thorpe2018\" />Passive House design is about managing heat loss and heat gain (not just from the sun but from all sources). The intended result is to have a structure that requires minimal energy to heat and cool.<ref name=\"thorpe2018\" />As such, some state that passive house design has greater applicability than solar design since orientation with respect to the sun is not absolutely necessary. Passive House design does not necessarily require a structure which is elongated along the east-west axis with extensive glazing on the equator facing side. Indeed, the ideal form of a passive house is a cube (lower surface area to volume ratio).<ref name=\"thorpe2018\" />Passive solar houses are also said to be more complicated to design, and the internal temperature may fluctuate uncomfortably if they are designed poorly.<ref name=\"GBA2010\">[https://www.greenbuildingadvisor.com/article/solar-versus-superinsulation-a-30-year-old-debate Solar Versus Superinsulation: A 30-Year-Old Debate]. Martin Holladay. Green Building Advisor, 2010</ref> Proponents of superinsulation state that compared to solar houses, greater savings can be obtained by building air tight with lots of insulation in walls and high R windows.<ref name=\"GBA2010\" />So, while some consider that the debate between passive solar and superinsulation resulted in the wider acceptance of superinsulation,<ref name=\"GBA2010\" />a more efficient approach would potentially be to utilise both passive solar and passive house design elements, which has been termed '''\"Solar Passivhaus\"'''.<ref name=\"thorpe2018\" />The remainder of this article therefore deals with passive solar in the modern sense of the term which is overlapping that of passive house design (rather than the original passive solar concepts in the 70s and 80s).\n\n== Passive annual heat storage ==\n\n{{Excerpt|Passive annual heat storage}}\n\n== Related projects ==\n\n{{Gallery\n| property = Project type\n| value = Passive solar design\n}}\n\n== See also ==\n\n{{Solar footer}}\n\n== External links ==\n\n* [http://www.ourcoolhouse.com/podcast/OurCoolHouse-Pasive_Solar_Design.mp3 Passive Solar Design] (MP3 audio file). Clear and basic explanation from the [http://www.ourcoolhouse.com/podcast/ OurCoolHouse Podcast]\n\n== References ==\n\n<references />\n\n{{Page data\n| keywords = Passive solar design, active solar design, passive house, sunlight, direct gain, indirect gain, isolated systems, thermal collector, temperature, thermal transfer, building design, key design techniques\n| sdg = SDG07 Affordable and clean energy, SDG09 Industry innovation and infrastructure, SDG11 Sustainable cities and communities, SDG12 Responsible consumption and production, SDG13 Climate action\n| published = 2010\n| license = CC-BY-SA-3.0\n| language = en\n| description = Passive solar design reduces heating costs through smart orientation and shading. Appropedia explains strategies that make buildings energy-efficient naturally.\n}}\n\n[[Category:Solar]]\n[[Category:Architecture]]\n[[Category:Passive solar]]"}