Solar architecture is an architectural approach that takes in account the Sun to harness clean and renewable solar power. It is related to the fields of optics, thermics, electronics and materials science. Both active and passive solar housing skills are involved in solar architecture. The use of flexible thin-film photovoltaic modules provides fluid integration with steel roofing profiles, enhancing the building’s design. Orienting a building to the Sun, selecting materials with favorable thermal mass or light dispersing properties, and designing spaces that naturally circulate air also constitute solar architecture. Initial development of solar architecture has been limited by the rigidity and weight of standard solar power panels. The continued development of photovoltaic (PV) thin film solar has provided a lightweight yet robust vehicle to harness solar energy to reduce a building’s impact on the environment.
In the past, we’ve seen solar panels as a necessary evil. They used to be clunky, awkward objects placed haphazardly around a building. Solar panels have evolved in their design and so to has their presence in the world of architecture and design. The major development in solar panels is that they no longer need to be perfectly flat. This has opened up a world of opportunities in their use in more abstract architectural projects. They have their limits, however. It’s hard for solar panels to soak up as much sunlight on an angle.
Architects have managed to take solar panels leaps and bounds. Panels have been incorporated into roofing without simply being placed in rows along a roof. Clients who choose to focus on solar energy can work with architects to designate flat, unused spaces throughout a property to place solar panels without drawing too much attention. More creatively, solar panels have been incorporated into awnings. They have also been incorporated into the landscaping of properties, dividing gardens and filling in empty spaces in the surrounding environment.
The effectiveness of solar architecture is largely determined by the creativity of the architect and the flexibility of the client. A clever architect will be able to incorporate solar panels into the design of a building without making them look bulky and awkward. The more a client is willing to be flexible with the amount of solar energy generated, the more subtly the panels can be incorporated into the design.
Solar panels have been widely available for purchase since the 1980s but have yet to be widely adopted in residential housing.
Some barriers to the widespread adoption of solar panels include worries about the cost of the panels, the impact on jobs, and their appearance.
“Economics is the biggest barrier, and aesthetics are the second,” Gardzelewski says. He says these two things stand in the way of solar becoming the standard for architecture design, rather than a risky and costly add-on.
The economic aspect of solar panels is multifaceted. First, there’s cost and risk perception, and then there’s the larger impact on the economy, such as the creation of green-collar jobs. Some people think that their home’s resale value is at risk when they install solar. One appraiser Gardzelewski spoke to said: “I won’t give a house with solar panels any more value in an appraisal. The appraisal will be the same with or without them.” Because the appraisal industry itself is ambivalent about assigning value to solar panels, many homeowners fear that installing them could actually decrease the value of their home—despite
potential savings for buyers on future energy bills.
The initial cost of installing solar panels is notoriously exorbitant. Gardzelewski insists that the actual price of the panels has decreased tremendously, so there is no reason that
solar-panel installation costs should remain so high. “Solar-panel installers will give you a quote to put solar panels on your home, and they will tell you it costs a lot more than it should cost or what it needs to cost,” he says. “The panels themselves have come down to where they’re just a fraction of the overall expense.”
One reason solar installation remains such a high-ticket item is that builders haven’t wholeheartedly adopted it. “Once solar integrates into the home-building industry, the price of labor will go down because the contractor is going to manage that pretty tightly,” Gardzelewski says. “If you manage the cost and the labor of solar-panel installation, there’s no room for the price to get jacked way up.”
In coal-industry-driven states, there is also some fear that the rise of solar energy will hurt the economy and take away jobs. But Gardzelewski disagrees. He believes that the long-standing blue-collar jobs of the coal industry could become the long-standing green-collar jobs of the solar industry.
BERG’s 5-Strategy Taxonomy for Solar Architecture
1. Legibility
This refers to revealing and celebrating the building systems to see how they work. This is an industrial look with the “guts” of the building exposed. In this paradigm, seeing the inner workings, wiring, structure, and connection of the solar panels fits in with the overall industrial design.
An energy-systems plan (including a radiant-floor heating system, insulation, seasonal shade structures, a ground-source heat pump, and design-integrated solar) for the Fox House in Pavilion, WY. Courtesy of UW-BERG.
2. Material Planes
Gerrit Rietveld’s
Schroder House and Ludwig Mies van der Rohe’s
Barcelona Pavilion are two examples of buildings focused on planar composition. In the case of the Barcelona Pavilion, Mies used planar composition to celebrate the richness of materials such as glass, marble, onyx, and travertine. With this strategy, the material aspect of a solar panel is celebrated, too. “We really love looking at the crystals and the wiring and all the intricacies of a solar panel,” Gardzelewski says.
3. Form Follows
From the principle “
form follows function,” this concept means designing a building that adapts its shape to the path of the sun. This strategy is obvious when a design is altered to provide optimal orientation for a large number of solar panels, often with a stretched-out or swooping form on the south roof. “A solar panel is a huge module of 3 1/2 feet by 5 1/2 feet, and this can seriously influence the size of your roof,” Gardzelewski says. Designing a roof to fit this module can make the actual solar installation not only easier and more effective but also much better looking.
4. Shading Through Solar Architecture
Solar panels can provide shade for the building itself or the adjacent outdoor space; this method is a good solution for a difficult existing roof. “If you build an exterior structure and you can pull out an enclosed porch—a space that you’re not trying to fit onto the existing roof—you can use it to shade a small space outside,” he says. “You can add solar panels to this new area, and it won’t have to blend into the rest of the roof, because it is a completely separate thing.”
A 3D model of the Fox House in Pavillion, WY. Courtesy of UW-BERG.
5. Disguised Solar-Panel Design
In this approach, the solar panels are hidden through either compositional strategy or design innovation. This strategy is best used in conjunction with “form follows,” as architecture designed around the size and shape of a solar panel is best suited to disguise the panel (like these
solar rooftops from Tesla). “If you can fit them perfectly onto your roof, then you can float or frame the solar panels so you don’t see all of the infrastructure under it—you just see the reflective glass,” Gardzelewski says.
Getting the economic equation for solar panels to work for average middle- and working-class families may take some time. But incorporating BERG’s architectural taxonomy, which integrates solar panels in the design phase, is something architects can do now. Even if a client isn’t going to install solar right away, the taxonomy can help home and building owners incorporate solar panels more aesthetically down the road. And by considering solar as an early constraint that influences building design, architects may be able to usher in an era when solar is finally ubiquitous.
Solar architecture
The term solar architecture refers to an approach to building design that is sensitive to Nature and takes advantage of climatic conditions to achieve human comfort rather than depending on artificial energy that is both costly and environmentally damaging. Unlike the conventional design approach that treats climate as the enemy which has to be kept out of the built environment, solar architecture endeavours to build as part of the environment using climatic factors to our advantage and utilising the energy of Nature itself to attain required comfort levels. Nature’s energies can be utilised in two ways – passiveand active and consequently solar architecture is classified as passive solar and active solar architecture.
Passive solar architecture
It relies upon the design or architecture of the building itself to ensure climate control by way of natural thermal conduction, convection and radiation. The rudiments of solar passive design were developed and used through the centuries by many civilisations across the globe; in fact, many of these early civilisations built dwellings that were better suited to their climatic surroundings than those built today in most developed and developing countries. This has been largely due to the advent of cheap fossil fuels that allowed for artificial temperature and light control at the cost of natural light and cooling. A substantial share of world energy resources is therefore being spent in heating, cooling and lighting of such buildings. The use of solar passive measures such as natural cross ventilation, sufficient day-lighting, proper insulation, use of adequate shading devices coupled with auxiliary energy systems that are renewable and environment friendly can considerably bring down the costs as well as the energy needs of the building.
Passive solar systems
The term passive solar refers to systems that absorb, store and distribute the sun’s energy without relying on mechanical devices like pumps and fans, which require additional energy. Passive solar design reduces the energy requirements of the building by meeting either part or all of its daily cooling, heating and lighting needs through the use of solar energy.
Passive heating
Heating the building through the use of solar energy involves the absorption and storage of incoming solar radiation, which is then used to meet the heating requirements of the space. Incoming solar radiation is typically stored in thermal mass such as concrete, brick, rock, water or a material that changes phase according to temperature. Incoming sunlight is regulated by the use of overhangs, awnings and shades while insulating materials can help to reduce heat loss during the night or in the cold season. Vents and dampers are typically used to distribute warm or cool air from the system to the areas where it is needed. The three most common solar passive systems are direct gain, indirect gain and isolated gain. A direct gain system allows sunlight to windows into on occupied space where it is absorbed by the floor and walls. In the indirect gain system, a medium of heat storage such as wall, in one part of the building absorbs and stores heat, which is then transferred to the rest of the building by conduction, convection or radiation. In an isolated gain system, solar energy is absorbed in a separate area such as greenhouse or solarium, and distributed to the living space by ducts. The incorporation of insulation in passive systems can be effective in conserving additional energy.
Passive cooling
Passive solar technology can also be used for cooling purposes. These systems function by either shielding buildings from direct heat gain or by transferring excess heat outside. Carefully designed elements such as overhangs, awnings and eaves shade from high angle summer sun while allowing winter sun to enter the building. Excess heat transfer can be achieved through ventilation or conduction, where heat is lost to the floor and walls. A radiant heat barrier, such as aluminium foil, installed under a roof is able to block upto 95% of radiant heat transfer through the roof.
Water evaporation is also an effective method of cooling buildings, since water absorbs a large quantity of heat as it evaporates. Fountains, sprays and ponds provide substantial cooling to the surrounding areas. The use of sprinkler systems to continually wet the roof during the hot season can reduce the cooling requirements by 25%. Trees can induce cooling by transpiration, reducing the surrounding temperature by 4 to 14 degrees F.
Active cooling systems of solar cooling such as evaporative cooling through roof spray and roof pond and desiccant cooling systems have been developed alongwith experimental stratergies like earth-cooling tubes and earth-sheltered buildings. Desiccant cooling systems are designed to dehumidify and cool air. These are particularly suited to hot humid climates where air-conditioning accounts for a major portion of the energy costs. Desiccant materials such as silica gels and certain salt compounds naturally absorb moisture from humid air and release the moisture when heated, a feature that makes them re-useable. In a solar desiccant system, the sun provides the energy to recharge the desiccants. Once the air has been dehumidified, it can be chilled by evaporative cooling or other methods to provide relatively cool, dry air. This can greatly reduce cooling requirements
Evaporative cooling
Evaporation occurs whenever the vapour pressure of water is lesser than the water vapour in the surrounding atmosphere. The phase change of water from liquid to the vapour state is accompanied by the release of a large quantity of sensible heat from the air that lowers the temperature of air while its moisture content increases. The provision of shading and the supply of cool, dry air will enhance the process of evaporative cooling. Evaporative cooling techniques can be broadly classified as passive and hybrid.
Passive direct systems include the use of vegetation for evapotranspiration, as well as the use of fountains, pools and ponds where the evaporation of water results in lower temperature in the room. An important technique known as ‘Volume cooler’ is used in traditional architecture. The system is based on the use of a tower where water contained in a jar or spray is precipitated. External air introduced into the tower is cooled by evaporation and then transferred into the building. A contemporary version of this technique uses a wet cellulose pad installed at the top of a downdraft tower, which cools the incoming air.
Passive indirect evaporative cooling techniques include roof spray and roof pond systems.
Roof spray
The exterior surface of the roof is kept wet using sprayers. The sensible heat of the roof surface is converted into latent heat of vaporisation as the water evaporates. This cools the roof surface and a temperature gradient is created between the inside and outside surfaces causing cooling of the building. A reduction in cooling load of about 25% has been observed. A threshold condition for the system is that the temperature of the roof should be greater than that of air.
There are, however, a number of problems associated with this system, not least of which is the adequate availability of water. Also it might not be cost effective, as a result of high maintenance costs and also problems due to inadequate water proofing of the roof.
Roof pond
The roof pond consists of a shaded water pond over an non-insulated concrete roof. Evaporation of water to the dry atmosphere occurs during day and nighttime. The temperature within the space falls as the ceiling acts as a radiant cooling panel for the space, without increasing indoor humidity levels. The limitation of this technique is that it is confined only to single storey structure with flat, concrete roof and also the capital cost is quite high.
Earth cooling tubes
These are long pipes buried underground with one end connected to the house and the other end to the outside. Hot exterior air is drawn through these pipes where tit gives up some of its heat to the soil, which is at a much lower temperature at a depth of 3m to 4m below the surface. This cool air is then introduced into the house.
Special problems associated with these systems are possible condensation of water within the pipes or evaporation of accumulated water and control of the system. The lack of detailed data about the performance of such systems hinders the large-scale use of such systems.
Earth-sheltered buildings
During the summer, soil temperatures at certain depths are considerably lower than ambient air temperature, thus providing an important source for dissipation of a building’s excess heat. Conduction or convection can achieve heat dissipation to the ground. Earth sheltering achieves cooling by conduction where part of the building envelope is in direct contact with the soil. Totally underground buildings offer many additional advantages including protection from noise, dust, radiation and storms, limited air infiltration and potentially safety from fires. They provide benefits under both cooling and heating conditions, however the potential for large scale application of the technology are limited; high cost and poor day-lighting conditions being frequent problems.
On the other hand, building in partial contact with earth offer interesting cooling possibilities. Sod roofs can considerably reduce heat gain from the roof. Earth berming can considerably reduce solar heat gain and also increase heat loss to the surrounding soil, resulting in increase in comfort.
Active solar architecture
It involves the use of solar collectors and other renewable energy systems like biomass to support the solar passive features as they allow a greater degree of control over the internal climate and make the whole system more precise. Active solar systems use solar panels for heat collection and electrically driven pumps or fans to transport the heat or cold to the required spaces. Electronic devices are used to regulate the collection, storage and distribution of heat within the system. Hybrid systems using a balanced combination of active and passive features provide the best performance.
Active solar systems
Active heating
In active systems, solar collectors are used to convert sun’s energy into useful heat for hot water, space heating or industrial processes. Flat-plate collectors are typically used for this purpose. These most often use light-absorbing plates made of dark coloured material such as metal, rubber or plastic that are covered with glass. The plates transfer the heat to a fluid, usually air or water flowing below them and the fluid is used for immediate heating or stored for later use. There are two basic types of liquid based active systems- open loop and closed loop. An open loop system circulates potable water itself, through the collector. In closed loop systems, the circulating fluid is kept separate from the system used for potable water supply. This system is mainly used to prevent the freezing of water within the collector system. However, there is no need to go in for such a system in India, as freezing of water is not a possibility. Also closed loop systems are less efficient as the heat exchanger used in the system causes a loss of upto 10 degrees in the temperature of water, at the same time, one has to reckon with the extra cost of the heat exchanger as well as the circulating pumps. Compared to these, thermosiphon systems are more convenient and simple.
In Thermosiphon systems, the water circulates from the collector to the storage tank by natural convection and gravity. As long as the absorber keeps collecting heat, water keeps being heated in the collector and rises into the storage tank, placed slightly above (at least 50 cm). The cold water in the tank runs into the collector to replace the water discharged into the tank. The circulation stops when there is no incident radiation. Thermosyphon systems are simple, relatively inexpensive and require little maintenance and can be used for domestic applications.
Solar ponds have been developed ,which harness the sun’s energy that can be used for various purposes including production of electricity.
Other devices such as solar cookers, water distillation systems, solar dryers, etc. have been developed which can be used to reduce energy requirements in domestic households and in industrial applications.
Active cooling
Absorption cooling systems transfer a heated liquid from the solar collector to run a generator or a boiler activating the refrigeration loop which cools a storage reservoir from which cool air is drawn into the space. Rankine steam turbine can also be powered by solar energy to run a compressed air-conditioner or water cooler.
Solar refrigeration is independent of electric supply and without any moving parts, for example, Zeolite refrigerator.
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