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Buildings overview

Contents

Introduction

The buildings industry sector includes the construction and operation of residential, commercial, industrial, and institutional buildings, ranging from the choice of building materials and form to the selection and operation of in-building equipment such as appliances. This sector is a highly fragmented and diverse one; taking the United States building industry as an example, actors within the industry include raw and finished materials suppliers; construction firms; architects, designers, and engineers; developers (who commission, finance, and operate buildings); property management firms; private owners such as homeowners; and a highly diverse set of tenants. While the design business is dominated from a volume perspective by larger firms (firms with more than 100 employees make up only 2% of all design firms but account for more than one third of total billings[1]), a significant portion of design business is served by a wide variety of smaller firms as well. The developer and property manager segments are quite diverse as well, spanning a variety of potential business plans and target tenants; as a result, their design considerations may vary widely.

Many of the parties described above have some input into energy- and emissions-related decisions. Primary decision-makers include the architects, engineers, and designers responsible for designing buildings, and their clients - typically developers. The preferences of property management firms, tenants, and private owners may influence design choices by applying market pressure for or against particular energy options. In addition, property managers, tenants, and private owners all exercise control over which improvements and appliances to install or use.

Building Sector Energy Trends

The building industry represents a significant portion of global total emissions, both currently and in the projected future - typically a third or more of total energy use and associated emission [2], depending on accounting systems; the IPCC Working Group III report[3] estimates that building sector emissions represent about a quarter of the global total carbon dioxide emissions. Within the highly developed United States, 72% of all electricity and 55% of natural gas is consumed in residential and commercial buildings[4].In 2004, the IPCC Working Group III report estimated that buildings sector emissions were approximately 8.6 GtCO2, including both embodied emissions (emissions embodied in the materials used to construct buildings) and energy used during operations). Of this total, 3 Gt were direct emissions, while the remainder were due to electricity use. At current projected baseline growth, they are expected to grow to 11.1 Gt/year in 2020 and 14.3 Gt/year in 2030.

Within the building industry, current emissions are the result of average annual growth in CO2 emissions between 1971 and 2004 of about 2.5% per year for commercial buildings and 1.7% per year for residential (yielding an average overall growth rate of 2% per year). In recent years, however, these trends have changed, with residential buildings' growth slowing (0.1%) while commercial buildings have grown faster (3.0%) [5].

Overall Prospects for Mitigation

Projection of future energy trends are inherently uncertain. However, the IPCC Working Group III report's aggregate of multiple models suggests that approximately 29% of projected baseline emissions in 2020 could be avoided cost-effectively, with an additional 3% and 4% of baseline emissions that could be avoided at up to 20 US$/tCO2 and 100 US$/tCO2, respectively[6]: in absolute terms, an estimated 3.2, 3.6, and 4.0 billion tons of CO2-eq. The IPCC report extrapolates this to 31% (4.5 billion tons), 4% additional (total of 5.0 billion tons), and 5% additional (total of 5.6 billion tons) at zero, 20, and 100 US$/tCO2, respectively. The IPCC report asserts that these estimates - particularly those at higher costs and later times - may underestimate the true mitigation potential because they do not account for all efficiency options, do not account for non-technological options such as changes to behavior, and do not necessarily account for potential synergies that could be captured by holistic design approaches.

Greenhouse gas reduction within the building field consists of:

  1. Reducing energy consumption
  2. Substituting low-emissions on-site solutions for off-site electrical power sources
  3. Reducing embodied energy in buildings
  4. Controlling emissions of non-CO2 GHG gases
  5. Changing source energy generation strategies: reducing emissions generated by building electricity consumption by switching to renewable energy sources and low-carbon fuels (for a more general discussion of this last topic, which applies to any sector that generates emissions via consumption of electricity, see renewable energy sources and low-carbon fuels).

Of the measures contained in these categories, the IPCC Working Group III report finds that the most promising in terms of cost effectiveness and size of potential savings include use of more efficient lighting and appliances; improved insulation, district heating, and heating-related measures (cooler climates) and cooling equipment upgrades (warmer climates); more efficient cooking stoves (developing countries); solar water heating; and building energy management systems. In general, integrated or whole building design approaches can increase both savings and cost effectiveness[7].

Reducing Energy Consumption

Reduction of energy consumption typically takes the form of one of a wide variety of efficiency technologies and strategies, including:

  1. Improvements to efficiency of in-building equipment, such as lighting, appliances, and refrigeration.
  2. Improvements to building insulation
  3. Minimization of outside air infiltration, using multiple glazing layers, low-emissivity coatings, low-conductivity framing materials, low-conductivity gases between glazing layers, solar radiation-reflective or absorptive glazing, weather stripping of doors and windows, sealing points of air leakage, and adding insulation in unconditioned spaces such as attics and basements and around pipe and ductwork. The impact of these technologies on localized heat flows can be high; the IPCC Working Group III report states that windows can be manufactured that have only 25-35% of the heat loss of standard non-coated double-glazed windows, or 15-20% of single-glazed windows[8].
  4. Improvements to building heating and cooling space conditioning systems
  5. Design of the building envelope to achieve space conditioning by selective filtering of solar radiation or outside air
  6. Building commissioning and quality control, including improved documentation; testing, performance monitoring, and review; and better operator training
  7. Behavioral changes and monitoring - the creation of financial incentives structures and information systems that allow and encourage building users to make more efficient energy consumption choices, including examples such as the use of tenant level billing and availability of plug load analysis to drive and support tenant-user efforts to conserve energy, and the use of occupancy sensors to automate some types of energy consumption choices
  8. Macro-level design decisions - including choice of building orientation and form and features such as self-shading and opportunities for passive ventilation and cooling
  9. Systems approaches to building design, which use an iterative design and operation process taking into account the building as an integrated and interactive system rather than a collection of isolated emissions reduction opportunities. The IPCC Working Group III report estimates the energy savings potential for this strategy as 35-50% for new commercial buildings[9]; advanced techniques may give up to 50-80%[10]
  10. Urban design, including considerations of density and building type and mix.

Low-Emissions On-Site Energy Substitutes

Strategies of this type can include:

  1. Use of passive solar design and on-site solar thermal and solar photovoltaic energy for generation of electricity, solar water heating, and space conditioning.
  2. Use of ground, ground water, aquifers and open bodies of water, or air as heat sources or heat sinks - directly, via heat pumps, or via evaporative cooling, radiative cooling, or earth-pipe cooling
  3. Where appropriate, the use of cogeneration or combined heat and power systems on or near building sites
  4. Where appropriate, use of fuel cell technology

Reducing Embodied Energy in Buildings

Embodied energy in building components consists of the amount of energy used to supply those components, including manufacture and transportation. While substituting materials with lower embodied emissions may result in overall emissions reduction, designers looking to minimize emissions must consider the tradeoff between initial embodied energy and overall lifecycle emissions for the building if substitute materials result in lower operations efficiency.

Controlling Emissions of non-CO2 GHG Gases

Halocarbon emissions minimization is possible in air conditioning and refrigeration technologies. Key sources of these types of emissions include CFC chillers and [[HFC supermarket refrigeration systems, as well as foam products, such as insulation and fire protection systems. Major releases often occur during decomissioning, removal, and destruction of these materials.

Retrofits

Retrofitting is necessary to address sub-optimal efficiency in the large stock of existing buildings. Primary and often cost-effective steps include addressing points of air leakage such as those around windows, doors, fixtures, plumbing, and others; improving insulation of areas such as attics, basements, walls, and pipe/ductwork, and weather stripping of doors and windows. More aggressive measures include external insulation and finishing systems (EIFSs), which can improve insulation and air-tightness, and installation of solar thermal and solar photovoltaic systems.

The potential for energy savings from relatively simple measures is meaningful: studies suggest that air sealing can save 15-20% of annual heating and air conditioning energy use (US houses)[11], and that homes in the US lose around one quarter of heating and cooling energy through duct leaks in unconditioned spaces.[12] Studies that have looked at a broader variety of cost-effective energy savings measures found savings potential ranging from 25-30% (Canadian houses built before the 1940s) to 12% (Canadian houses built in the 1990s)[13] to 35% (houses in the United Kingdom), with the potential for up to 50% or more at modest or greater cost[14]. EIFSs can produce even higher savings, with decreases in energy requirement of up to 75%[15]. A range of studies suggests an energy savings of 50-75% in commercial buildings is possible through "aggressive implementation of integrated sets of measures," justified by energy-cost savings as well as consideration of less tangible benefits. However, such retrofits may require knowledgeable, competent retrofit teams which may be hard to find[16]; advanced techniques may give up to 50-80%[17][18].

Co-Benefits

Emissions reduction measures offer co-benefits to society that may be more difficult to demonstrate or quantify in economic or financial analysis, but may include reduction in air pollution; improvements in health, quality of life, and social welfare; increased productivity and business opportunities; and the potential for greater energy security.

Barriers to Adoption

Although many sources argue that a significant percentage of building emissions mitigation measures are actually cost-effective, adoption in many cases remains low. A number of barriers to adoption exist:

First, the traditional linear design process makes it difficult to carry out the type of integrated, iterated design process that can most effectively capitalize on the potential for effective use of efficiency measures.

Second, the building industry's market structure, fragmentation, and wide variety in project and building size impose limitations on adoption. Because end-users of building space and equipment are typically not involved in the design process, and in existing business models are often charged flat fees for utilities including energy, there is little incentive for end-users, whose energy choices affect total consumption, to make low-consumption choices; and it is difficult to create effective market pressure for efficiency measures. In addition, in the case of smaller projects, the potential rewards of these projects are not large enough to tempt investors or justify transaction costs such as verifying information and negotiating contracts necessary to support efficiency measures.

Third, in general, imperfect information is a problem for efficiency measures in the building industry; potential users suffer from lack of awareness of a variety of technologies and find it difficult to obtain trustworthy, complete information on options. Lack of centralized information and testing and reliable modeling leads to difficulties in learning and applying techniques and accurately projecting potential pay-back of possible efficiency measures, making these measures riskier and more difficult to justify. Dealing with this problem involves solutions such as improvements in building information modeling techniques; greater standardization of testing, measurement, and application; and better clearinghouses for efficiency information.

Fourth, government policies may retard adoption of emissions reduction measures. These can include regulatory barriers, like variations in permitting and metering policies, energy subsidies, which can lower the effective cost of energy and thus undermine financial incentives that might otherwise drive adoption.

Fifth, cultural, traditional, and behavioral issues can lead to resistance to adoption or use of efficiency measures.

Business and Policy Model Responses

A variety of proposed business and policy model responses intended to overcome barriers and drive adoption of emissions-reducing technologies and systems are either in use now or have been proposed:

  1. Changes to industry structure intended to shift the structure of financial incentives toward efficiency, such as a move to tenant level billing
  2. Changes to help reduce barriers created by lack of information, standardization, or competence, such as the creation and support by government or industry groups of standard professional codes of conduct and certification programs like the Leadership in Energy and Environmental Design (LEED) Certification
  3. Direct regulation such as building code mandates and limits on building energy use
  4. Efforts to shift energy price signals by raising the total cost of energy, such as a tax on energy use or a tax on carbon emissions

References

  1. ↑ "The Business of Architecture: 2006 AIA Firm Survey", (The American Institute of Architects, 2006)
  2. ↑ Cheng, C., Pouffary, S., Svenningsen, N., Callaway, M., "The Kyoto Protocol, the Clean Development Mechanism, and the Buildings and Construction Sector - a Report for the UNEP Sustainable Buildings and Construction Initiative", (Paris, France: United Nations Environment Programme, 2008)
  3. ↑ Levine, M., D. Orge-Vorsatz, K. Blok, L. Geng, D. Harvey, S. Lang, G. Levermore, A. Mongameli Mehlwana, S. Mirasgedis, A. Novikova, J. Rilling, H. Yoshino, 2007, "Residential and Commercial Buildings". In Climate Change 2007: Mitigation, Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [B. Metz, O.R. Davidson, P.R. Bosch, R. Dave, L.A. Meyer (eds)], (Cambridge, United Kingdom and New York, NY: Cambridge University Press, 2007)
  4. ↑ COMPLETE get ref from Gary
  5. ↑ Levine, M., D. Orge-Vorsatz, K. Blok, L. Geng, D. Harvey, S. Lang, G. Levermore, A. Mongameli Mehlwana, S. Mirasgedis, A. Novikova, J. Rilling, H. Yoshino, 2007, "Residential and Commercial Buildings". In Climate Change 2007: Mitigation, Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [B. Metz, O.R. Davidson, P.R. Bosch, R. Dave, L.A. Meyer (eds)], (Cambridge, United Kingdom and New York, NY: Cambridge University Press, 2007)
  6. ↑ Levine, M., D. Orge-Vorsatz, K. Blok, L. Geng, D. Harvey, S. Lang, G. Levermore, A. Mongameli Mehlwana, S. Mirasgedis, A. Novikova, J. Rilling, H. Yoshino, 2007, "Residential and Commercial Buildings". In Climate Change 2007: Mitigation, Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [B. Metz, O.R. Davidson, P.R. Bosch, R. Dave, L.A. Meyer (eds)], (Cambridge, United Kingdom and New York, NY: Cambridge University Press, 2007)
  7. ↑ Levine, M., D. Orge-Vorsatz, K. Blok, L. Geng, D. Harvey, S. Lang, G. Levermore, A. Mongameli Mehlwana, S. Mirasgedis, A. Novikova, J. Rilling, H. Yoshino, 2007, "Residential and Commercial Buildings". In Climate Change 2007: Mitigation, Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [B. Metz, O.R. Davidson, P.R. Bosch, R. Dave, L.A. Meyer (eds)], (Cambridge, United Kingdom and New York, NY: Cambridge University Press, 2007)
  8. ↑ Levine, M., D. Orge-Vorsatz, K. Blok, L. Geng, D. Harvey, S. Lang, G. Levermore, A. Mongameli Mehlwana, S. Mirasgedis, A. Novikova, J. Rilling, H. Yoshino, 2007, "Residential and Commercial Buildings". In Climate Change 2007: Mitigation, Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [B. Metz, O.R. Davidson, P.R. Bosch, R. Dave, L.A. Meyer (eds)], (Cambridge, United Kingdom and New York, NY: Cambridge University Press, 2007 COMPLETE)
  9. ↑ Levine, M., D. Orge-Vorsatz, K. Blok, L. Geng, D. Harvey, S. Lang, G. Levermore, A. Mongameli Mehlwana, S. Mirasgedis, A. Novikova, J. Rilling, H. Yoshino, 2007, "Residential and Commercial Buildings". In Climate Change 2007: Mitigation, Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [B. Metz, O.R. Davidson, P.R. Bosch, R. Dave, L.A. Meyer (eds)], (Cambridge, United Kingdom and New York, NY: Cambridge University Press, 2007)
  10. ↑ Harvey, L.D.D., A Handbook on Low-Energy Buildings and District Energy Systems: Fundamentals, Techniques, and Examples. (London: James and James, 2006)
  11. ↑ Francisco, P.W., L. Palmiter, and B. Davis, "Modeling the Thermal Distribution Efficiency of Ducts: Comparisons to Measured Results," Energy and Buildings 28 (1998) pp. 287-297
  12. ↑ Rosenfeld, A.H., "The Art of Energy Efficiency: Protecting the Environment with Better Technology." Annual Review of Energy and the Environment 24 (1999), pp. 33-82
  13. ↑ Parker, P., I.H. Rowlands, and D. Scott, "Assessing the Potential to Reduce Greenhouse Gas Emissions in Waterloo Region Houses: Is the Kyoto Target Possible?", Environments 28:3, (2000) pp. 29-56
  14. ↑ Bell, M. and R. Lowe, "Energy Efficient Modernisation of Housing: A UK Case Study", Energy and Buildings 32 (2000) pp. 267-280
  15. ↑ Humm, O., "Ecology and Economy When Retrofitting Apartment Buildings", IEA Heat Pump Centre Newsletter 15:4 (2000) pp. 17-18
  16. ↑ Levine, M., D. Orge-Vorsatz, K. Blok, L. Geng, D. Harvey, S. Lang, G. Levermore, A. Mongameli Mehlwana, S. Mirasgedis, A. Novikova, J. Rilling, H. Yoshino, 2007, "Residential and Commercial Buildings". In Climate Change 2007: Mitigation, Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [B. Metz, O.R. Davidson, P.R. Bosch, R. Dave, L.A. Meyer (eds)], (Cambridge, United Kingdom and New York, NY: Cambridge University Press, 2007)
  17. ↑ Harvey, L.D.D., A Handbook on Low-Energy Buildings and District Energy Systems: Fundamentals, Techniques, and Examples. (London: James and James, 2006)
  18. ↑ Rosenfeld, A.H., "The Art of Energy Efficiency: Protecting the Environment with Better Technology", Annual Review of Energy and the Environment 24 (1999), pp. 33-82
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