Sustainable architecture is a branch of architecture that focuses on the design and construction of buildings according to environmental sustainability criteria, with the aim of minimizing their negative environmental impact by enhancing efficiency, reducing material and energy consumption, and minimizing the disturbance to the surrounding ecosystem. Sometimes, sustainable architecture may also focus on the social aspect of sustainability. Social sustainability concerns sustainable handling the everyday positive and negatives of running a business. This includes the impacts that the negatives and positives have on each individual. architecture relies on social sustainability to guide the topic towards its true goal. Sustainable architecture uses a conscious approach to energy and ecological conservation in the design of the built environment.
The concept of sustainability, or ecological design, ensures that the use of current resources does not adversely affect future society's well-being or render it impossible to obtain resources for other uses in the long term.
Background
Shift from narrow to broader approach
The term "sustainability" in relation to architecture has so far been mostly considered through the lens of building technology and its transformations. Going beyond the technical sphere of "green design", invention and expertise, some scholars are starting to position architecture within a much broader cultural framework of the human interrelationship with nature. Adopting this framework allows for tracing a rich history of cultural debates about humanity's relationship to nature and the environment, from the point of view of different historical and geographical contexts.
Changing pedagogues
Critics of the reductionism of modernism often noted the abandonment of the teaching of architectural history as a causal factor. The fact that a number of the major players in the deviation from modernism were trained at Princeton University's School of Architecture, where recourse to history continued to be a part of design training in the 1940s and 1950s, was significant.
The increasing rise of interest in history had a profound impact on architectural education. History courses became more typical and regularized. With the demand for professors knowledgeable in the history of architecture, several PhD programs in schools of architecture arose in order to differentiate themselves from art history PhD programs, where architectural historians had previously trained. In the US, MIT and Cornell were the first, created in the mid-1970s, followed by Columbia, Berkeley, and Princeton. Among the founders of new architectural history programs were Bruno Zevi at the Institute for the History of Architecture in Venice, Stanford Anderson and Henry Millon at MIT, Alexander Tzonis at the Architectural Association, Anthony Vidler at Princeton, Manfredo Tafuri at the University of Venice, Kenneth Frampton at Columbia University, and Werner Oechslin and Kurt Forster at ETH Zürich.Mark Jarzombek, "The Disciplinary Dislocations of Architectural History," Journal of the Society of Architectural Historians 58/3 (September 1999), p. 489. See also other articles in that issue by Eve Blau, Stanford Anderson, Alina Payne, Daniel Bluestone, Jeon-Louis Cohen and others.
Operational carbon vs embodied carbon
Global construction accounts for 38% of total global emissions. While sustainable architecture and construction standards have traditionally focused on reducing operational carbon emissions, there are to date few standards or systems in place to track and reduce embodied carbon. While steel and other materials are responsible for large-scale emissions, cement alone is responsible for 8% of all emissions.
Sustainable energy use
Energy efficiency over the entire life cycle of a building is a primary goal of sustainable architecture. Architects use many different passive and active techniques to reduce the energy needs of buildings and increase their ability to capture or generate their own energy.M. DeKay & G.Z. Brown, Sun Wind & Light, architectural design strategies, 3rd ed. Wiley, 2014 To minimize cost and complexity, sustainable architecture prioritizes passive systems to take advantage of building location with incorporated architectural elements, supplementing with renewable energy sources and then fossil fuel resources only as needed. Site analysis can be employed to optimize use of local environmental resources such as daylight and ambient wind for heating and ventilation.
Energy use very often depends on whether the building is on-grid or off-grid. Off-grid buildings do not use energy provided by utility services and instead have their own independent energy production. They use on-site electricity storage while on-grid sites feed in excessive electricity back to the grid.
Heating, ventilation and cooling system efficiency Numerous passive architectural strategies have been developed over time. Examples of such strategies include the arrangement of rooms or the sizing and orientation of windows in a building, and the orientation of facades and streets or the ratio between building heights and street widths for urban planning.M. Montavon, Optimization of Urban Form by the Evaluation of the Solar Potential, EPFL, 2010
An important and cost-effective element of an efficient heating, ventilation, and air conditioning (HVAC) system is a well-insulated building. A more efficient building requires less heat generating or dissipating power, but may require more ventilation capacity to expel polluted indoor air.
Significant amounts of energy are flushed out of buildings in the water, air and compost streams. Off the shelf, on-site energy recycling technologies can effectively recapture energy from waste hot water and stale air and transfer that energy into incoming fresh cold water or fresh air. Recapture of energy for uses other than gardening from compost leaving buildings requires centralized anaerobic digesters.
HVAC systems are powered by motors. Copper, versus other metal conductors, helps to improve the electrical energy efficiencies of motors, thereby enhancing the sustainability of electrical building components.
Site and building orientation have some major effects on a building's HVAC efficiency.
Passive solar building design allows buildings to harness the energy of the sun efficiently without the use of any active solar mechanisms such as photovoltaic cells or solar hot water panels. Typically, passive solar building designs incorporate materials with high thermal mass that retain heat effectively and strong insulation that works to prevent heat escape. Low energy designs also require the use of solar shading, by means of awnings, blinds or shutters, to reduce the solar heat gain in summer and to reduce the need for artificial cooling.
In addition, low energy buildings typically have a very low surface area to volume ratio to minimize heat loss. This means that sprawling multi-winged building designs (sometimes thought to look more "organic") are generally avoided in favor of more centralized structures. Traditional cold climate buildings such as American colonial saltbox designs provide a good historical model for centralized heat efficiency in a small-scale building.
Windows are placed to maximize the input of heat-creating light while minimizing the loss of heat through glass, a poor insulator. In the northern hemisphere this usually involves installing a large number of south-facing windows to collect direct sun and severely restricting the number of north-facing windows. Certain window types, such as double or triple glazed insulated windows with gas filled spaces and low emissivity (low-E) coatings, provide much better insulation than single-pane glass windows.
Preventing excess solar gain by means of solar shading devices in the summer months is important to reduce cooling needs. Deciduous trees are often planted in front of windows to block excessive sun in summer with their leaves but allow light through in winter when their leaves fall off. Louvers or light shelves are installed to allow the sunlight in during the winter (when the sun is lower in the sky) and keep it out in the summer (when the sun is high in the sky). They are slatted like shutters and reflect light and radiation to reduce glare on the interior space. Advanced louver systems are automated to maximize daylight and monitor the interior temperature by adjusting their tilt. Coniferous or evergreen plants are often planted to the north of buildings to shield against cold north winds.
In colder climates, heating systems are a primary focus for sustainable architecture because they are typically one of the largest single energy drains in buildings.
In warmer climates where cooling is a primary concern, passive solar designs can also be very effective. Masonry building materials with high thermal mass are very valuable for retaining the cool temperatures of night throughout the day. In addition builders often opt for sprawling single story structures in order to maximize surface area and heat loss. Buildings are often designed to capture and channel existing winds, particularly the especially cool winds coming from nearby bodies of water. Many of these valuable strategies are employed in some way by the traditional architecture of warm regions, such as south-western mission buildings.
In climates with four seasons, an integrated energy system will increase in efficiency: when the building is well insulated, when it is sited to work with the forces of nature, when heat is recaptured (to be used immediately or stored), when the heat plant relying on fossil fuels or electricity is greater than 100% efficient, and when renewable energy is used.
Renewable energy generation
Solar panels
Active solar devices such as photovoltaic solar panels help to provide sustainable electricity for any use. Electrical output of a solar panel is dependent on orientation, efficiency, latitude, and climate—solar gain varies even at the same latitude. Typical efficiencies for commercially available PV panels range from 4% to 28%. The low efficiency of certain photovoltaic panels can significantly affect the payback period of their installation. This low efficiency does not mean that solar panels are not a viable energy alternative. In Germany, for example, solar panels are commonly installed in residential home construction.
Roofs are often angled toward the sun to allow photovoltaic panels to collect at maximum efficiency. In the northern hemisphere, a true-south facing orientation maximizes yield for solar panels. If true-south is not possible, solar panels can produce adequate energy if aligned within 30° of south. However, at higher latitudes, winter energy yield will be significantly reduced for non-south orientation.
To maximize efficiency in winter, the collector can be angled above horizontal Latitude +15°. To maximize efficiency in summer, the angle should be Latitude -15°. However, for an annual maximum production, the angle of the panel above horizontal should be equal to its latitude.G.Z. Brown, Mark DeKay. Sun, Wind & Light. 2001
Wind turbines
The use of undersized wind turbines in energy production in sustainable structures requires the consideration of many factors. In considering costs, small wind systems are generally more expensive than larger wind turbines relative to the amount of energy they produce. For small wind turbines, maintenance costs can be a deciding factor at sites with marginal wind-harnessing capabilities. At low-wind sites, maintenance can consume much of a small wind turbine's revenue.Brower, Michael; Cool Energy, The Renewable Solution to Global Warming; Union of Concerned Scientists, 1990 Wind turbines begin operating when winds reach 8 mph, achieve energy production capacity at speeds of 32-37 mph, and shut off to avoid damage at speeds exceeding 55 mph.