Latest Updates: FIU Presidential Search | Healthy Living | Statement of Free Expression
Module01kcere0032019-02-27T15:14:59+00:00
Sustainability of Buildings
Among all human activities contributing to climate change, design and construction of buildings is the most energy demanding, resource-intensive, and polluting. Buildings and their operations in the in U.S. alone are responsible for the consumption of three billion tons of raw materials, 49% of the nation’s total energy, and 77% of its electricity each year [1]. Materials utilized in constructing buildings have high-embodied energy, high carbon emissions and high levels of toxins and pollutants in their production cycle. It is estimated that buildings contribute as much as one third of total global greenhouse gas (GHG) emissions primarily through the use of fossil fuels during their operational phase [3].
As the environmental impact of buildings become increasingly recognized, the role of building architects, engineers and Construction managers in the decision-making process which determines materials, systems, and construction processes become more critical. Thus, an informed design process merging environmentally responsible practices with advanced technologies can significantly reduce the adverse impact of buildings on the environment.
The following is an excerpt from the Best Practice for Sustainable design Book. For further information please see best practices in sustainable building design. J. Ross publishing.
Designing buildings based on climate appropriate strategies entails utilizing, analyzing and interpreting climatic data properly. Data collected based on climatic zones provide a vast range of information on air temperature, humidity, precipitation, solar radiation, natural light, wind, and vegetation. Making informed early stage design decisions based on this data is critical in evaluating climate responsive strategies alternatives, which can lead to superior building energy performance. The following sections briefly describe how climatic information could be utilized in the building design process.
Building in Hot and Humid Climates
The hot and humid climatic condition is found in lower latitudes close to the Equator and is mostly identified by the lack of seasonal variation and intense solar radiation for most of the year. In this climate, the east and west sides of a building receive low altitude sunrays that produce large heat gains. This is a result of the incident sun striking the building’s surface with close to right angles on the east and west. To reduce heat gain, it is best to minimize the building’s dimensions on these sides.Using diffused light from the north side can reduce glare in addition to minimizing solar heat gain. Proper overhangs on southern glazing will allow the admission of low angle winter sunlight for daylighting and exclude excessive higher angle solar radiation in the warmer summer months. Average wind speeds are generally low and less frequent in the hot and humid climates and the prevailing winds are from the south and southeast during the overheated period. Buildings with narrow floor plans and openings on the two sides, oriented perpendicular to the air flow, will benefit most from cross ventilation.
Plan Geometry
Buildings with elongated footprints perform well in the hot climates of lower latitudes. Plan geometries that form shallow floor depths are ideal in this climatic zone since they maximize cross ventilation and provide ample access to natural light.
Surface to Volume Ratio
A Large surface to volume ratio can lead to significant heat exchange through the building skin.
Building Orientation
Minimizing the plan dimensions in the east and west can reduce solar heat gain significantly.
Natural Lighting
Admitting diffused light from the north will provide natural lighting, reducing the energy required for artificial lighting.
Mass and Service Core
Placing the building’s service core along the east and west sides will reduce heat gain by providing shaded zones, thus reducing the temperature.
Natural Ventilation
Window openings, perpendicular to the prevailing winds’ direction, facilitate cross ventilation.
Buildings in Hot and Arid Climates
Hot and arid climates receive little precipitation and typically have daily temperatures that are higher than night time temperatures. In general, plan geometries that form shallow floor depths are ideal in this climatic zone since they maximize cross ventilation, allow for night cooling, and provide ample access to natural light. Similar to buildings located in hot and humid climates, a building orientation with the short sides facing east and west is most effective in reducing exposure to intense solar radiation. With predominantly clear blue skies and bright ground surfaces in the hot and arid climatic zones, it is best to admit diffused light or reflected light from the ground or louver surfaces. Admitting light from the north reduces solar heat gain as well as glare. Utilizing proper overhangs on southern glazing will allow low angle winter sunlight for daylighting and reflect the intense high angle sunlight in the warmer summer months. When possible, it is best to avoid glazing and place shear walls or service cores on the hot east and west sides of the building. When placed in the periphery, the core spaces serve as thermal buffers reducing solar penetration into the interior of the building. Circulation spaces can also create buffer zones to protect the building from excessive sun penetration. Evaporative cooling is an effective cooling strategy in hot and arid climates. This process produces cooler temperatures by moving dry air through moisture. As there is often a great difference between the daily and nightly temperatures, night cooling can remove much of the daily generated heat leading to lower early morning interior temperatures. The prevailing winds in hot and arid climates are from the east and west directions during the overheated period.
Plan Geometry
Buildings with elongated footprints perform well in the hot climates of lower latitudes. Plan geometries that form shallow floor depths are ideal in this climatic zone since they maximize cross ventilation, allow for night cooling, and provide ample access to natural light.
Surface to Volume Ratio
Large surface to volume ratio can lead to significant heat exchange through the building skin.
Building Orientation
Minimizing the plan dimensions in the east and west can reduce solar heat gain significantly.
Natural Lighting
Admitting diffused light or reflected light from the north will provide natural lighting, reducing the energy required for artificial lighting.
Mass and Service Core
Placing the building’s service core along the east and west sides will provide shaded zones reducing heat gain and the building’s temperature.
Natural Ventilation
Perpendicular orientation of window openings to the prevailing winds facilitates cross ventilation. Evaporative cooling systems and night cooling are effective methods to lower air temperatures in hot and arid climates.
Building in Temperate Climatic Zones
The moderate temperatures, light winds and four distinctively marked seasons of the temperate climates provide more flexibility in the selection of the building form. The implementation of passive strategies, maximizing heat gain during winter months and minimizing heat gain during the summer, can be very effective in these climates. Since the larger the surface area of a building, the greatest potential for heat exchange with the exterior environment, orienting the long surfaces of the building to the south will provide direct passive heating in winter months. Placing windows on the south side can facilitate access to high levels of illumination reducing the energy required for artificial lighting. As the prevailing winds are from the south and southwest, window openings are best located on the windward façades to facilitate cross ventilation during summer months. However, it is best to restrict incoming fresh air during the winter. The difference in temperature between the interior of the building and the exterior environment allows a stack effect to draw in fresh air. Shear walls, service cores and circulation spaces are best located on the north side of the building to reduce heat loss.
Plan Geometry
Elongation of the form along the east and west axis is preferable as it provides a larger exposed surface for passive heating in the south side of the building during the winter.
Surface to Volume Ratio
Large surface to volume ratios can lead to significant heat exchange through the building skin. Large surface areas should be oriented towards the south to capture solar energy for passive heating during the winter.
Building Orientation
The long surfaces of the building should be oriented towards the south to capture solar energy.
Natural Lighting
Admitting light from south facing exposed glass walls, provides ample natural light in addition to providing passive heating. However, direct sunlight through the southern façade should be controlled in order to minimize glare and visual discomfort.
Mass and Service Core
Shear walls, service core and circulation spaces are best located on the north side of the building to reduce heat loss.
Natural Ventilation
Window openings on the windward south and southwest sides and the leeward north and northeast sides will facilitate cross ventilation.
Buildings in Cool Climatic Zones
In the higher latitudes of the north hemisphere with colder climates, it is best to minimize the surface exposed to the cold winter winds and reduce heat loss. In these climates, buildings are best oriented to receive maximum solar radiation. In general, aligning the long axis of the built form along the east-west axis provides maximum solar exposure on the south façade maximizing passive heat gain.Direct sunlight can be an excellent source of lighting in cool climates if efficiently distributed throughout the building. However, direct sunlight through the southern façade should be controlled in order to minimize glare and visual discomfort. In these climates, service cores should be located at the center of the building to allow solar penetration from the perimeter for passive heating. The circulation spaces are best to be located on the north side of the building to provide a thermal buffer that mitigates exterior lower temperatures. Natural ventilation can be achieved using wind pressure or stack effects. Adequate air exchange through small openings is preferable to maintain comfortable interior temperatures and avoid excessive heat loss. The prevailing winds come from the northwest during the winter months and south and southeast during the heated period. Cross ventilation during the summer months can be effective to reduce significantly the energy required for mechanical cooling systems.
Plan Geometry
Elongation of the form along the east and west axis is preferable as it provides larger exposure in the south side of the building for passive heating.
Surface to Volume Ratio
Large surface to volume ratios can lead to significant heat exchange through the building skin. Large surface areas should be oriented towards the south to capture solar energy for passive heating.
Building Orientation
The long surfaces of the building should be oriented towards the south to capture solar energy.
Natural Lighting
Admitting light from south facing exposed glass walls can provide ample natural light and passive heating. However, direct sunlight through the southern façade should be controlled in order to minimize glare and visual discomfort.
Mass and Service Core
Shear walls and service cores are best located at the center of the building to allow solar penetration from the perimeter for passive heating. The circulation spaces are best located on the north side of the building to provide a thermal buffer that mitigates exterior lower temperatures.
Natural Ventilation
Natural ventilation can be achieved using wind pressure or stack effects. Adequate air exchange through small openings is preferable to maintain comfortable interior temperatures and avoid excessive heat loss. Window openings on the windward northwest sides and the leeward southeast sides will facilitate cross ventilation.
The following is an excerpt from the Complexity of Sustainable and Resilient Building Design and Urban Development Chapter in Sustainability and Social Responsibility of Accountability Reporting Systems.
Mitigation Strategies
There many strategies that can be used to reduce energy consumption and minimize the carbon-foot print of buildings. However, these strategies are sometimes in conflict or may not align well with broader building objectives such as owners’ priorities, building location, or the financial constraints of the project. This makes the process of building design a balancing act that requires input and guidance from multiple resources.
To create an overall understanding of possible strategies to mitigation, the table shown here provides a series of design measures in relation to Building Design, Urban Form and Landscape Systems. In this table, the strategies for Building Design are categorized into two subgroups of Building Configuration, and Materials and Assemblies. Building Configuration involves decisions about building geometry, volume, orientation, and the exposed surface area to the environment. Appropriate strategies for Building Configuration place a high priority on climatic conditions of the building site often leading to significant energy saving. These strategies prioritize the use of natural cooling, heating and ventilation (passive controls) over the use mechanical systems (active controls). They also emphasize the use of natural light over artificial lighting. For example, a building located in a cold climate with an elongated shape along the east and west axis and openings on the south side, can utilize solar heat and access daylight, thus reducing energy demand.
Contrarily when designing in hot and dry climates, minimizing the building dimensions in the east-west direction reduces solar heat gain. In addition, placing building services such as elevators and stairs in the east-west direction blocks direct sunlight and create buffer zones. Shallow floor depths in these climatic conditions provide ample daylight and maximize cross ventilation and night cooling if the building openings are located on the long sides of the building to utilize prevailing winds.
Building Materials and Assemblies are another important factor in determination of building performance. Materials with high thermal efficiency used in building enclosures control heat- gain and heat- loss significantly. For example, wood has a higher resistance to heat transfer than concrete and steel. Therefore, using wood in building facades could be an effective strategy in particular climatic conditions. Some materials such as concrete, masonry or stone have the capacity to absorb and store solar heat. When properly used, they can absorb heat energy deep into their mass during the day and slowly release it during nighttime.
There are also new technologies and materials such as Phase Change Material (PCM) that can store energy and release it at a later time. PCM can be incorporated into wallboards, roofs, celling and floors to passively cool or heat buildings (Vassigh, Ozer, and Speiegelhalter 2013). It is critically important to have all building connections sealed off to prevent a higher rate of heat transfer at connections, particularly in cold climatic zones. Using airtight connections and placing insulation materials in vulnerable areas often achieve this. Using airtight connections also helps with endurance of the building exterior materials as it prevents moisture accumulation at the connection vicinity where the hot and cold air meets.
Another important aspect of material use in buildings is the evaluation of their environmental impact. Construction materials use energy and water in their production and transportation to the building site. Embodied energy is defined as the energy used during the entire life cycle of a material including the energy used for manufacturing, transporting, and disposing (Lippke et al. 2004). Similarly, embodied water indicates the amount of water used to produce, transport and dispose of a material. As indicated in the table, selecting materials with lower Embodied Energy and Embodied Water will reduce the carbon-foot print of buildings. Unfortunately, Embodied Energy and Water are often overlooked in lieu of other considerations.
The next category of strategies for sustainable development addresses the larger context of development in the Urban Form. The table, subdivides Urban Form into two closely related subcategories of Dense Construction and Mixed-Use Buildings. Constructing buildings, neighborhoods and larger communities in densely configured patches has multiple benefits. Density reduces energy used for commuting significantly. When properly coupled with designing Mixed Use Building strategies, it creates incentives for people to commute less as they are able to walk to work and amenities. In addition, dense development makes the use of public transit more feasible. However, to achieve this, the zoning codes and planning priorities should be significantly revised and incentives for developers and all other involved parties should be expanded. Dense development should be carefully planned as it may be in conflict with other strategies that prioritize reducing traffic and air pollution.
The last section of the table lists some of the numerous and effective sustainable strategies that can be provided by Landscape Systems. Divided into Thermal Efficiency and Hydrological Efficiency subcategories (Vassigh, Ozer, Spiegelhalter, 2013), these strategies can be applied at the small scale of individual buildings as well as the large scale of the urban environment and beyond. Landscape systems can shield buildings from solar heat. Using canopy shading, vegetated surfaces, green walls and roofs can moderate solar heat gain. In addition, Landscape Systems protects buildings from wind and facilitate natural ventilation.
Landscape systems can be used to mitigate air, water and soil pollution. For example, large leaved indigenous evergreens mitigate airborne pollution. Vegetative filter strips such as orchards, vineyards, and row crops remove pollutants from runoff water while providing some degree of resistance to soil erosion. Certain species of plants remove or degrade contaminates from soil and water through their internal process thus providing an economically viable method to control pollution (Kumar et al. 2013).
The following is an excerpt from the Complexity of Sustainable and Resilient Building Design and Urban Development Chapter in Sustainability and Social Responsibility of Accountability Reporting Systems.
Climate Change challenge
Climate change is presenting new challenges to the built environment by increasing both the intensity and frequency of extreme events. High temperatures, sustained high winds, weather fluctuations, flooding, drought, and sea level rise set the context in which our buildings and their infrastructure must exist and remain usable. These events generate significant stresses such as intensified wind impact on building structures, wind driven rain intrusion into buildings through facades, storm surge, and intense flooding. In addition, the consequences of sea-level rise on building systems, materials, and foundations can be devastating.
Generating public sector support in order to develop the appropriate actions for adaptation to climate change impacts has been difficult for a number of reasons: first, the public’s disbelief and the lack of recognition of the risks and threats; second, the absence of appropriate risk assessment and decision making support tools; third, the anticipated high cost of long-term benefits with little or no immediate payback, and finally, the lack of adequate and enforceable policies for building in new conditions.
Three sections of tables shown here provide an overview of a series of adaptation strategies for climate change. It categorizes various adaptive approaches for three major climate change impacts including Rising Temperature, Storms and Hurricanes, and Sea Level Rise. Measures for addressing each impact is subdivided into three interconnected scales of Buildings, Community and the Urban Environment.
Table 1.1 lists a number of strategies for combating higher temperatures at the building scale. These strategies revolve around extensive use of green walls and green roofs, trees and vegetated surfaces, in order to provide thermal insulation and shade to reduce temperature. Designing to maximize natural ventilation in buildings is another way of combating high temperatures. However, as the temperature rises, the use of outside air for cooling building’s interior space becomes less feasible.
Measures for resilient construction for extreme events such as storms and hurricane for buildings include simpler configurations that offer better resistance to high winds. Minimizing exposed surface area and using continuous joinery and connections in buildings are among other strategies to increase resistance to the wind impact. Measures to combat water from storms and hurricanes in buildings include water-proofing foundations, use of water resistant materials in building facades to protect against wind driven rain, and designing ground levels to allow passage of flood water. Methods to address the impact of sea level rise in buildings include construction of sea walls, using compacted earth fills and raising buildings on piles above the flood levels. In addition, relocating all building services and mechanical equipment to higher floors eliminates water damage in storm surge or flooding.
Table 1.1 Resilient Design and Development for Buildings
The measures at the community scale are listed in table 1.2. Using landscape strategies, reflective roofs, and reduced impervious surfaces are among measures to remediate high temperature. To control the impact of storms and hurricanes, clustered planning of buildings can be very effective. Grouping buildings in close proximity in staggered patterns reduces wind-tunneling effect thus controlling damage.
Table 1.2 Resilient Design and Development for Community
High-density development, listed in Table 1 as a sustainability measure, is also a highly effective resiliency approach to manage storm water. Dense construction can reduce impervious surfaces such as roads, parking lots and paved sidewalks that cannot absorb the storm runoff and can be easily flooded. Measures for combating sea level rise in low-lying and vulnerable areas include moving entire communities to higher elevations or retreat from the area.
Table 1.3 addresses appropriate measures at the urban scale. The urban environment has a microclimate condition called Urban Heat Island effect, which is a local increase in temperature due to high density of buildings with hard surface, high density of transportation activities, and generation of wasted heat from buildings. As temperature rise heightens this condition, utilizing trees and green belts moderates the Heat Island Effect. In addition, using heat recovery systems to remove wasted heat from buildings and converting usable energy is increasingly a technologically and economically viable solution.
To control the impact of storm and hurricane -generated water, the reduction of impervious surfaces can control runoff water. In addition, constructing treatment wetlands for cleansing storm water and placing green space along flood lanes are appropriate measures.
Table 1.3 Resilient Design and Development for the Urban Environment
Among strategies to protect the urban environment from the impact of sea level rise in the costal zones reestablishing sand dunes is critical. According to FEMA, due to over development some sand dunes have been completely destroyed. Rebuilding sand dunes and preserving them with coastal vegetation can protect large areas further inland, which enhancing the Appearance of the beaches (FEMA 2007). Other measures include creating earthen levees; beach nourishment to replace eroding beaches, increased coastal set back requirements and elevating critical infrastructure (Hamin and Gurran, 2009).
The discussion above offers a range of possible mitigation and adaptation strategies for climate change. However, providing an expansive list of measures to address every impact of climate change on the built environment is not the ultimate goal, and is beyond the scope of this article. The objective here is to reveal the scale and complexity of issues.
The following sections shift the focus on building design and development processes and examines how to implement these strategies.