Building Construction Illustrated

John Wiley & Sons

Chapter One

1.02 BUILDING IN CONTEXT

Buildings do not exist in isolation. They are conceived to house, support, and inspire a range of human activities in response to sociocultural, economic, and political needs, and are erected in natural and built environments that constrain as well as offer opportunities for development. We should therefore carefully consider the contextual forces that a site presents in planning the design and construction of buildings.

The microclimate, topography, and natural habitat of a site all influence design decisions at a very early stage in the design process. To enhance human comfort as well as conserve energy and material resources, responsive and sustainable design respects the indigenous qualities of a place, adapts the form and layout of a building to the landscape, and takes into account the path of the sun, the rush of the wind, and the flow of water on a site.

In addition to environmental forces, there exist the regulatory forces of zoning ordinances. These regulations take into account existing land-use patterns and prescribe the acceptable uses and activities for a site as well as limit the size and shape of the building mass and where it may be located on the site.

Just as environmental and regulatory factors influence where and how development occurs, the construction, use, and maintenance of buildings inevitably place a demand on transportation systems, utilities, and other services. A fundamental question we face is how much development a site can sustain without exceeding the capacity of these service systems, consuming too much energy, or causing environmental damage.

Consideration of these contextual forces on site and building design cannot proceed without a brief discussion of sustainability.

SUSTAINABILITY 1.03

In 1987, the United Nations World Commission on Environment and Development, chaired by Gro Harlem Brundtland, former Prime Minister of Norway, issued a report, Our Common Future. Among its findings, the report defined sustainable development as "a form of development that meets the needs of the present without compromising the ability of future generations to meet their own needs."

Increasing awareness of the environmental challenges presented by climate change and resource depletion has pushed sustainability into becoming a significant issue shaping how the building design industry operates. Sustainability is necessarily broad in scope, affecting how we manage resources as well as build communities, and the issue calls for a holistic approach that considers the social, economic, and environmental impacts of development and requires the full participation of planners, architects, developers, building owners, contractors, manufacturers, as well as governmental and non-governmental agencies.

In seeking to minimize the negative environmental impact of development, sustainability emphasizes efficiency and moderation in the use of materials, energy, and spatial resources. Building in a sustainable manner requires paying attention to the predictable and comprehensive outcomes of decisions, actions, and events throughout the life cycle of a building, from conception to the siting, design, construction, use, and maintenance of new buildings as well as the renovation process for existing buildings and the reshaping of communities and cities.

1.04 GREEN BUILDING

The terms "green building" and "sustainable design" are often used interchangeably to describe any building designed in an environmentally sensitive manner. However, sustainability calls for a whole-systems approach to development that encompasses the notion of green building but also addresses broader social, ethical, and economic issues, as well as the community context of buildings. As an essential component of sustainability, green building seeks to provide healthy environments in a resource-efficient manner using ecologically based principles.

Green building is increasingly governed by standards, such as the Leadership in Energy and Environmental Design (LEED[R]) Green Building Rating System[TM], which provides a set of measurable criteria that promote environmentally sustainable construction. The rating system was developed by the U.S. Green Building Council (USGBC) as a consensus among its members-federal/state/local agencies, suppliers, architects, engineers, contractors, and building owners-and is continually being evaluated and refined in response to new information and feedback. In July 2003 Canada obtained a license from the USGBC to adapt the LEED rating system to Canadian circumstances.

LEED GREEN BUILDING RATING SYSTEM 1.05

LEED]R]

To aid designers, builders, and owners achieve LEED certification for specific building types and phase of a building life cycle, the USGBC has developed a number of versions of the LEED rating system:

LEED-NC: New Construction and Major Renovations

LEED-CI: Commercial Interiors

LEED-CS: Core/Shell

LEED-EB: Existing Buildings

LEED-Homes

LEED-ND: Neighborhood Developments

LEED for Schools

LEED for Healthcare

LEED for Labs

LEED for Retail

The LEED rating system for new construction addresses six major areas of development.

1. Sustainable Sites deals with reducing the pollution associated with construction activity, selecting sites appropriate for development, protecting environmentally sensitive areas and restoring damaged habitats, encouraging alternative modes of transportation to reduce the impact of automobile use, respecting the natural water hydrology of a site, and reducing the effects of heat islands.

2. Water Efficiency promotes reducing the demand for potable water and the generation of wastewater by using water-conserving fixtures, capturing rainwater or recycled graywater for conveying sewage, and treating wastewater with on-site systems.

3. Energy & Atmosphere encourages increasing the efficiency with which buildings and their sites acquire and use energy, increasing renewable, nonpolluting energy sources to reduce the environmental and economic impacts associated with fossil fuel energy use, and minimizing the emissions that contribute to ozone depletion and global warming.

4. Materials & Resources seeks to maximize the use of locally available, rapidly renewable and recycled materials, reduce waste and the demand for virgin materials, retain cultural resources, and minimize the environmental impacts of new buildings.

5. Indoor Environmental Quality promotes the enhanced comfort, productivity, and wellbeing of building occupants by improving indoor air quality, maximizing daylighting of interior spaces, enabling user control of lighting and thermal comfort systems to suit task needs and preferences, and minimizing the exposure of building occupants to potentially hazardous particulates and chemical pollutants, such as the volatile organic compounds (VOC) contained in adhesives and coatings and the urea-formaldehyde resins in composite wood products.

6. Innovation & Design Process rewards exceeding the requirements set by the LEED-NC Green Building Rating System and/or demonstrating innovative performance in Green Building categories not specifically addressed by the LEED-NC Green Building Rating System.

1.06 THE 2030 CHALLENGE Climate Change & Global Warming

Greenhouse gases, such as carbon dioxide, methane, and nitrous oxide, are emissions that rise into the atmosphere. C[O.sup.2] accounts for the largest share of U.S. greenhouse gas emissions. Fossil fuel combustion is the main source of C[O.sup.2] emissions.

Architecture 2030 is an environmental advocacy group whose mission is "to provide information and innovative solutions in the fields of architecture and planning, in an effort to address global climate change." Its founder, New Mexico architect Edward Mazria, points to data from the U.S. Energy Information Administration that indicates buildings are responsible for almost half the total U.S. energy consumption and greenhouse gas (GHG) emissions annually; globally, Mazria believes the percentage is even greater.

What is relevant to any discussion of sustainable design is that most of the building sector's energy consumption is not attributable to the production of materials or the process of construction, but rather to operational processes-the heating, cooling, and lighting of buildings. This means that to reduce the energy consumption and GHG emissions generated by the use and maintenance of buildings over their life span, it is necessary to properly design, site, and shape buildings and incorporate natural heating, cooling, ventilation, and daylighting strategies.

The 2030 Challenge issued by Architecture 2030 calls for all new buildings and developments to be designed to use half the fossil fuel energy they would typically consume, and that an equal amount of existing building area be renovated annually to meet a similar standard. Architecture 2030 is further advocating that the fossil fuel reduction standard be increased from to 60% in 2010, 70% in 2015, 80% in 2020, and 90% in 2025, and that by 2030, all new buildings be carbon-neutral (using no fossil-fuel GHG-emitting energy to build and operate).

There are two approaches to reducing a building's consumption of GHG-emitting fossil fuels. The passive approach is to work with the climate in designing, siting, and orienting a building and employ passive cooling and heating techniques to reduce its overall energy requirements. The active approach is to increase the ability of a building to capture or generate its own energy from renewable sources (solar, wind, geothermal, low-impact hydro, biomass and bio-gas) that are available locally and in abundance. While striking an appropriate, cost-effective balance between energy conservation and generating renewable energy is the goal, minimizing energy use is a necessary first step, irrespective of the fact that the energy may come from renewable resources.

Site analysis is the process of studying the contextual forces that influence how we might situate a building, lay out and orient its spaces, shape and articulate its enclosure, and establish its relationship to the landscape. Any site survey begins with the gathering of physical site data.

SITE ANALYSIS 1.07

Draw the area and shape of the site as defined by its legal boundaries.

Indicate required setbacks, existing easements, and rights-of-way.

Estimate the area and volume required for the building program, site amenities, and future expansion, if desired.

Analyze the ground slopes and subsoil conditions to locate the areas suitable for construction and outdoor activities.

Identify steep and moderate slopes that may be unsuitable for development.

Locate soil areas suitable for use as a drainage field, if applicable.

Map existing drainage patterns. (LEED SS Credit 6: Stormwater Design)

Determine the elevation of the water table.

Identify areas subject to excessive runoff of surface water, flooding, or erosion.

Locate existing trees and native plant materials that should be preserved.

Chart existing water features, such as wetlands, streams, watersheds, flood plains, or shorelines that should be protected. (LEED SS Credit 5: Site Development, Protect or Restore Habitat)

Map climatic conditions: the path of the sun, the direction of prevailing winds, and the expected amount of rainfall.

Consider the impact of landforms and adjacent structures on solar access, prevailing winds, and the potential for glare.

Evaluate solar radiation as a potential energy source.

Determine possible points of access from public roadways and public transit stops. (LEED SS Credit 4: Alternative Transportation)

Study possible circulation paths for pedestrians and vehicles from these access points to building entrances.

Ascertain the availability of utilities: water mains, sanitary and storm sewers, gas lines, electrical power lines, telephone and cable lines, and fire hydrants.

Determine access to other municipal services, such as police and fire protection.

Identify the scope of desirable views as well as objectionable views.

Cite potential sources of congestion and noise.

Evaluate the compatibility of adjacent and proposed land uses.

Map cultural and historical resources that should be preserved.

Consider how the existing scale and character of the neighborhood or area might affect the building design.

Map the proximity to public, commercial, medical, and recreational facilities. (LEED SS Credit 2: Development Density & Community Connectivity)

1.08 SOILS

There are two broad classes of soils-coarse-grained soils and fine-grained soils. Coarse-grained soils include gravel and sand, which consist of relatively large particles visible to the naked eye; fine-grained soils, such as silt and clay, consist of much smaller particles. The American Society for Testing and Materials (ASTM) Unified Soil Classification System further divides gravels, sands, silts and clays into soil types based on physical composition and characteristics. See table below.

The soil underlying a building site may actually consist of superimposed layers, each of which contains a mix of soil types, developed by weathering or deposition. To depict this succession of layers or strata called horizons, geotechnical engineers draw a soil profile, a diagram of a vertical section of soil from the ground surface to the underlying material, using information collected from a test pit or boring.

The integrity of a building structure depends ultimately on the stability and strength under loading of the soil or rock underlying the foundation. The stratification, composition, and density of the soil bed, variations in particle size, and the presence or absence of groundwater are all critical factors in determining the suitability of a soil as a foundation material. When designing anything other than a single-family dwelling, it is advisable to have a geotechnical engineer undertake a subsurface investigation.

A subsurface investigation (CSI MasterFormat 02 30 00) involves the analysis and testing of soil disclosed by excavation of a test pit up to 10' (3 m) deep or by deeper test borings in order to understand the structure of the soil, its shear resistance and compressive strength, its water content and permeability, and the expected extent and rate of consolidation under loading. From this information, the geotechnical engineer is able to gauge the anticipated total and differential settlement under loading by a proposed foundation system.

SOIL MECHANICS 1.09

The allowable bearing capacity of a soil is the maximum unit pressure a foundation is permitted to impose vertically or laterally on the soil mass. In the absence of geotechnical investigation and testing, building codes may permit the use of conservative load-bearing values for various soil classifications. While high-bearing-capacity soils present few problems, low-bearing-capacity soils may dictate the use of a certain type of foundation and load distribution pattern, and ultimately, the form and layout of a building.

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Excerpted from Building Construction Illustrated by Francis D.K. Ching Copyright © 2008 by Francis D.K. Ching. Excerpted by permission.
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Francis D.K. Ching is the bestselling author of numerous books on architecture and design, including Architecture: Form, Space, and Order, A Global History of Architecture, Architectural Graphics, A Visual Dictionary of Architecture, and Interior Design Illustrated, all published by Wiley. His works have been translated into over sixteen languages and are regarded as classics for their renowned graphic presentation. He is a registered architect and Professor Emeritus at the University of Washington in Seattle.