Homes need to be socially, economically, and environmentally sustainable in response to societal pressure on our common future. The concept of ‘Sustainable Development’ was first advocated by the World Commission on Environment and Development, dated back to 1987, and it was considered as ‘a process of change in which the exploitation of resources, the direction of investments, the orientation of technological development, and institutional change are all in harmony and enhance both current and future potential to meet needs and aspirations.’ In 1992, this notion was given additional impetus at the United Nations Conference on Environment and Development (or the Earth Summit) held in Rio de Janeiro where an initial international treaty on environment was produced; however, this had neither limits on green house gas emissions nor legal enforcement provisions for individual nations. In 1997, the text of the Kyoto Protocol to the United Nations Framework Convention on Climate Change was adopted eventually at the 3rd Conference of the Parties held in Kyoto, Japan. As of April 2008, 178 states signed and ratified the Protocol; in consequence, most industrialized nations and some central European countries agreed to legally binding the reductions of greenhouse gas emissions of an average of 6 to 8% below 1990 levels between the years 2008 and 2012.
Housing is a system of energy and environment. Homes are responsible for a great deal of carbon dioxide (CO2) emissions that encompass the enormous impact on global warming—for instance, CO2 emissions from the housing sector in the UK account for 27 per cent of the national carbon footprint to which each dwelling unit contributes on average 3 tons CO2 ¬ per year. How on earth can the CO2 emissions in housing be reduced or eliminated over the life cycle? Undoubtedly, the mass-production (and mass-marketing) of ‘zero carbon housing’ is the key to resolving the societal pressure. Prior to the discussion of carbon-neutral housing, the energy use in housing needs to be reduced to low or zero levels. In essence, zero energy housing falls into two categories: self-sustainable or net. The former type is a stand-lone house whose operational energy relies solely on its own power generation and storage so that it is disconnected from a commercial grid or disuses the power from the outside sources. The latter is the one whose energy ‘use’ becomes net zero over a fixed period of time. In addition, a house whose energy ‘bill’ becomes net zero under the same conditions is termed net zero-energy-cost housing. The notion of zero carbon housing today is from time to time likened to that of these abovementioned homes; perchance, the performance may entail the further steps to cover CO2 emissions that derive from not only the operation but also the construction and demolition—i.e. over the house’s life cycle.
In theory, homebuilders are keen on the marketability of their products and are sensitive to the market needs and demands, which somewhat change over time. In reality, the builders tend to follow ‘routines’ in their way of doing business and cut down information search for non-programmed decisions to determine whether or not to adopt unfamiliar design challenges, and innovative building materials and methods, which may somewhat require the reshaping of their ‘closed-system’ business operations. In order to propagate zero-carbon housing solutions, the technical information needs to be legible and the design approach and production process should be systematised. However, the concept and performance of zero-carbon housing today are not coherent and the logical sequence of the delivery process is so far little discussed. Accordingly, this special issue took the initiative in packaging the dispersed knowledge of potential zero carbon housing solutions. Inevitably, the scope of the discourses became diverse in subjects ranging from the analyses of existing low-energy housing and solar community developments, energy-efficient building materials, passive energy and environmental systems, renewable energy technologies to the investigations of design, production and marketing strategies for the delivery of marketable and replicable zero energy housing and the community development.
This MEARU edition was established with the aim to assist housing researchers and professionals in grasping the status quo of carbon-neutral housing in question and provide a base for their research and development activities. Expectantly, this collective expertise of international experts in eco-housing will also be fed into a policy making cycle for discussion of net metering, time zone contract and feed-in-tariff schemes, which are almost inevitable in the mass sales of net zero carbon homes today and tomorrow.