W.J. Batty

Vernacular architecture of Oman: Features that enhance thermal comfort achieved within buildings

Modern building developments in the Arab Gulf States have been accompanied by a recent rapid abandonment of adhering to energy-thrift principles as adopted in the vernacular architecture of the region. This has occurred despite the success of these types of buildings in providing thermal comport, by natural means for many hundreds of years, in the harsh environment of the region. The consequence of this abandonment has been the rapid increase in electricity-generating capacity to match demand (of which, for example, at present in Oman, more than 70% nationally is used for air-conditioning modern, energy-inefficient buildings). Considerable parts of these electricity loads represent unnecessary financial burdens upon the nations of the region. This study concentrates on how the vernacular architecture in one of the states in the region, namely the Sultanate of Oman, has in the past utilised successfully ambient-energy sources for achieving thermally comfortable artificial environments. To this end, the country has been considered as four significantly different climatic regions, namely, the coastal, mountainous, desert and southern regions. Lessons have been drawn from the performances of the various vernacular buildings in these regions: if implemented the resulting understanding should help lower the energy consumptions of modern buildings exposed to such climates.

Windows for buildings in hot arid countries

Too often, in the last 50 years, the energy-thrift lessons of vernacular architecture have been forgotten or ignored. In the Middle East, many recently-designed commercial buildings, with large areas of glazing, incur excessively high electricity-demands to provide energy for the required air-conditioning plant. One way of reducing the magnitude of this demand is through better window design. For this purpose, a new form of triple-glazed window is proposed to facilitate achieving improved thermal comfort within buildings, while simultaneously reducing the expenditures on purchased energy.

Natural-cooling techniques for residential buildings in hot climates

In most developing countries in the hot regions of the world during the last 50 years there have been many buildings constructed that are highly energy wasteful. The interiors of these buildings have to be mechanically air-conditioned in order to achieve thermal-comfort conditions. Consequently vast financial expenditures have and are being spent upon the installation and operation of the electricity-generating plants needed to supply the maximum power demand during summer. In many of these countries, air-conditioning accounts for more than 70% of the national electrical power consumption. However, less than a century ago, the inhabitants of these countries lived in buildings that incorporated only natural-cooling (i.e. far cheaper) techniques for achieving thermal comfort. In this paper, these tranditional beneficial techniques have been reviewed and the recent advances in both hybrid and active natural-cooling systems described.

Use of the thermal-probe technique for the measurement of the apparent thermal conductivities of moist materials

The thermal-probe technique has been assessed for use with moist materials. Initial investigations with wet clay specimens showed that the probe diameter had no signoficant effect on the indicated values of the apparent thermal conductivity. Tests to measure the apparent thermal conductivities of aerated concrete blocks, at various moisture contents and distributions, gave results that compared well with other published data.

Effects of operative behaviours and management planning on energy consumptions in kitchens

The ways in which individual catering appliances were used, as well as the planning of meal production, have been studied for five catering facilities (namely for 3 canteens, an hotel and a psychiatric hospital). For each kitchen, activity charts were deduced from the observed patterns of use of each appliance. Several of the identified practices, such as switching-on appliances well before necessary, incurred excessive energy consumptions. Other established habits, such as permitting inordinately-long cooking or holding periods for the food at elevated temperatures, increased energy consumptions and adversely affected the quality of the food produced. The undertaken surveys provided evidence for: 1. (i) the need to review existing practices within kitchens, in order to promote the adoption of more efficient operational procedures and equipment use; 2. (ii) the need, as a systematic requirement, to train staff in the effective uses of new appliances; 3. (iii) the incorporation of programmed timers to switch-on, as well as switch-off, equipment and so relieve staff of the worry that these items will not be at the desired temperatures (and so not be available for immediate use) when required; and 4. (iv) the removal from the kitchen of equipment which is no longer needed or is of low efficiency.

Energy and condensation problems in buildings

Buildings are complex thermally dynamic structures serving aesthetic, as well as utilitarian, functions. It is essential that careful planning is undertaken if buildings are to be energy efficient and cheap to run throughout their expected life-spans. Although regulations have been introduced recently requiring the values of the thermal transmittances (i.e. the U-values) for walls and roofs of industrial and domestic buildings to be less than specified limits, there is no guarantee that improved design will result. Also, condensation has become a more serious and widespread problem as natural ventilation is reduced by the introduction of double-glazing and draught-proofing.

Apparent thermal conductivities of high-porosity cellular insulants

Mathematical models of heat transfers through multi-phase materials have been examined. A model is proposed to describe the thermal conductivity of high-porosity cellular insulants: heat transfers by conduction through the solid and gaseous phases as well as by radiation are considered. Predictions were found to agree well with experimental data for air-filled polystyrene foams and to be of the correct order of magnitude for air/fluorocarbon-filled polyurethane foams.

Supply of, and demand for, a resource: Fuzzy logistical optimisation technique

Fuzzy logistical analysis for exploiting a resource helps determine the relative strengths and weaknesses of various supply-demand chains linking alternative sources (in the supply sector) to their final points of use (in the demand sector). There are benefits and constraints associated with each supply and demand sector. Fuzzy theory is applied to the logistical optimisation of these sectors in order to assess the relative importance or degree of association between the supply and demand determinants, which therefore should influence the decisions made for the exploitation strategies adopted for different sectors. Each supply determinant is related to each demand determinant. From their relative values of association, the relationship corresponding to each supply-demand pathway can be calculated and compared with those for the remaining pathways. Such information is valuable, for example when devising and implementing strategies affecting waste management and the recycling of materials and/or energy.

Design improvements for the ubiquitous electric toaster

Previous studies concerning bread-toasting operations, as well as the designs and performances of currently available domestic toasters are reviewed. Methods for improving the quality of the toast produced by a typical double-slot toaster, together with modifications which will raise its thermal efficiency and make it safer to use, are discussed. A controller is described which can compensate automatically for the initial non-ambient environmental temperature of the toaster (which is caused usually by an immediately preceding toasting operation), so that batches of toast of similar quality can be produced consistently. The findings from a survey concerning the toasteating habits of 250 adults are presented as an appendix.

Mathematical model for predicting the magnitudes of total, diffuse, and direct-beam insolation

The simple mathematical model presented assumes that: 1. (i) the characteristic diurnal distribution of the fraction of the incident solar radiation available outside the atmosphere that is received on a horizontal surface under clear-sky conditions can be expressed as a curve of the form [tau]gmr=Ae-cp[alpha]mr in which A is a scaling coefficient, mr is the relative air mass, and c[rho][alpha] is an attenuation factor which depends on the angle of incidence;2. (ii) the diffuse fraction can reasonably be described approximately as [tau]dmr[approximate]1-(Bmr+[tau]gmr) in which B is the broad-band absorptivity. Measured values for the solar irradiance recorded at 1 min time intervals at a rural location near Cambridge, UK, were used to examine the relationship between the fraction of the solar radiation received on a horizontal surface and the diffuse fraction. The measurements corroborate the predictions from the mathematical model, whose validity is thus supported.