Introduction

In the wake of costs for wave power, which have exceeded original estimates, interest in the UK is tending to concentrate on wind power as a means of central electricity generation using renewable sources of energy. In such northern latitudes the use of concentrating solar collectors for power generation is not viable.

For this reason a consortium of companies in conjunction with the North of Scotland Hydroelectric Board is about to construct a 3 MW turbine in the Orkneys, illustrated in Fig. 8.1. There are also tentative plans to place large fields of vertical-axis turbines in shallow parts of the North Sea off the east coast of England. These turbines would be of the Musgrove type shown in Fig. 8.15. Studies show that up to 30% of electricity in use at a given time in the UK could be supplied from variable inputs such as wind turbines, without upsetting the grid network. Southern California Edison expects a 30% contribution by 1991.

However, this chapter seeks to deal with small, local wind turbines. It has to be pointed out that the energy derived from wind-power devices is not unending (the turbines probably should have a lifetime of 20 years or so in the absence of freak weather), is not free (the devices are quite large and thus costly) and that to some, the machines are not handsome, and to others, represent a hazard.

It may help to provide a brief checklist of advantages and problems presented by the home use of wind power, before embarking on a description of the energy and devices available.

Introduction

Definitions

The somewhat arid discussion of the semantics of active hybrid and passive systems has been alluded to in the previous chapter.

Here, an active system is really taken to mean a bolt-on arrangement, which is usually not part of the building structure (for example, a solar hot-water heating system) and which often involves pumps or fans. Of course, some solar air heaters do form the roofs of buildings (see Section 5.2) and some hot-water systems flow naturally by a thermosiphon.

Popularity of solar heating

The UK Solar Trade Association assesses how widely such systems are used, and the 1981 figures show that there are 60 firms manufacturing solar systems or components or installing them. From 1974 to 1981, 173,000 m2 of collector were produced. About 21,000 m2 of hotwater system were installed in 1981, comprising about 5000 systems. About 2400 swimming-pool systems have been installed from 1974 to 1981. The main complaints seem to involve misunderstandings either by clients or manufacturers of the likely output or benefit of a given system. There has been no ‘Gallup Poll’ of users' reactions in the UK, but in the US a study for the Solar Energy Research Institute shows these conclusions: two-thirds of houseowners strongly wish to see solar energy developed over other sources; one-third of people feel solar is technically and economically practical today for homes; two-thirds of people have not considered investing in solar technology for their homes.

Introduction

Results from the recent Better Insulated Housing Programmed are summarized in Table 11.1 which shows the fractions of energy consumed onsite for various purposes.

The experimental houses at Bebington (Fig. 4.48), which are electrically heated, indicate that only about half the electricity supplied annually is used directly for space heating.

Much of the energy provided to the lights, fridge and so on, contributes usefully during the heating season to warming the space. Capper suggests the fractions shown in Table 11.2.

One might wish to argue a little with the low figures (Leach assumes 0.8 in all cases and Siviour's conclusions are shown in Table 3.1) but the fact remains that a substantial fraction of the heating in houses arises from electricity (or gas) used in appliances. Since this energy is wholly or partly electrical (generated with an efficiency of roughly 30%), the cost to the country in terms of primary fuel, or to the consumer in terms of cost, constitutes a large part of the annual fuel bill for each house. Thus, one would expect to find regulations concerning the efficiency of appliances. There are almost none in the UK, although in the US some goods must be marked with an efficiency indicator.

In the Bo'ness study, nearly all households have a clothes washer, one-third a tumble drier, all have a fridge and 40% have a freezer. Most have a colour television. Two-thirds of the households have electric fires, one-third have calor gas and one-fifth have paraffin heaters as subsidiary heating devices.

Introduction

Traditional site planning includes evaluation of the aesthetics of a site, population densities, land-use patterns, slope, drainage, soil characteristics, incident solar radiation, daylighting, exposure to wind and numerous other considerations which are treated in standard works.[1, 2] In this chapter these subjects will be discussed only when specifically applicable to the use of ambient energy sources or the opportunity for energy conservation in buildings. In the more recent past the attitude of many designers has been one of ignoring both the natural characteristics of the site and the potential of solar and wind energy. Instead, they concentrated merely on avoiding potentially deleterious effects such as summertime overheating.

Important exceptions to this way of thinking include Olygay & Givoni who wrote classic works on climate and architecture [3,4] In an age of rapidly dwindling fossil-fuel reserves, though, it is important to use a site to best advantage. Fortunately, much can be done to conserve energy merely through good design, on both the large and small scale. In the former category especially, the possibilities depend on social conceptions of work, home and leisure but in the future we may see a closer integration of places of work and residence to reduce transportation energy. This could be encouraged by a gradual renovation of cities, resulting in their increasing attractiveness as places of residence and thus reducing the tendency towards suburban sprawl. For example, near the city home of one of the present authors, a former warehouse is being converted into flats. Among the results are a higher density and, for the occupants, less dependence on vehicular transport.

Introduction

Surprisingly enough, several years ago one of the highlights in California Governor Jerry Brown's politics was the introduction of a law forbidding the sale of any lavatory which flushes more than 141 of water. Waste disposal does not often receive such publicity although the problems it entails in both industrialized and non-industrialized countries, albeit for different reasons in the two groups, are impressive.

Here we shall deal with wastes in greater detail than we did with water systems but not because the central network is less extensive – in the UK 94% of all households are connected to mains sewers (in the US, on the other hand, the comparable figure is about 67%). Rather, it is because wastes can be a source of on-site energy if methane digesters are used. Although this tends to be less practical at the level of a single home, groupings of houses and other building types such as schools should not ignore the energy potential of the wastes they produce.

Mains servicing in the UK, as elsewhere, consists of a cistern-flush toilet connected to a network of underground sewers which transport sewage and domestic waste water to a treatment or disposal facility. While to those of us who use such systems almost nothing seems more natural, it is of interest to note that the concept of using storm sewers for human wastes is only about 140 years old and the first integrated system only came into full use about 1870 in London. The first sewers merely conveyed the wastes to bodies of water where they were discharged with often disastrous consequences – sadly this practice continues today in many areas.

Introduction

This chapter takes the reader through some of the design processes which occurred during the planning of several low-energy houses. The Peterborough Houses are complex, having large air-heating solar collectors, a sophisticated ductwork system and microprocessor control. The Newnham Houses are more conventionally heated, but highly insulated. These new dwellings are discussed in Section 12.2, and in 12.3 reference is made to the rehabilitation of existing houses, including one with a passive roof-space solar collector.

New houses – three solar abdicated houses in Peterborough

The authors won a competition at the 1979 National Energy Show, for a terraced low-energy house, designed with Lucy Krall, shown in Fig. 12.1. Peterborough Development Corporation became interested after seeing the model on television and suggested that the same sort of principles could be applied to one of their houses.

In the end, a terrace of three was built, as shown in Fig. 12.2. Because a lot of domestic hot water was likely to be produced by large collectors, we felt that six-person houses should be built. Larger units also yielded a greater roof area than would smaller terraced houses. In fact, in order to provide a reasonably large area (32 m! gross), collectors were also placed on the first-storey walls.

In retrospect, this idea of dual slope collectors was probably influenced by the Autarkic House (Fig. 12.3) in which the architectural design forced the provision of collectors on three azimuths and two tilts. The whole of the southerly facade in the Peterborough Houses is glazed, since the ground floor consists of a conservatory opening into the living room.

Introduction

This chapter briefly presents some non-domestic buildings designed with energy conservation in mind.

The swimming pool, Sheiling Schools

Given the opportunity to design a swimming pool for a school for handicapped children, it was automatically part of the brief to keep the running costs to a minimum, despite the fact that water temperatures had to be maintained at 27 C for use throughout the year. The Energy Design Group made an initial study which investigated the potential of heat pumps and heat-reclaim systems, glazed and unglazed solar collectors, variable speed ventilation control and the use of a pool cover.

Initially it was felt that a heat-pump system would be preferable, using extract air as a primary source of heat. This, however, entailed expensive duct work to return the air to the boiler room, and also added considerably to the capital costs since an auxiliary gas-fired heater could not be dispensed with. Other heat-reclaim systems were dependent on the use of ozone or other very expensive purification systems which reduced their overall cost-effectiveness. (Chlorine from the pool is corrosive over the long term.)

The entire building was built to a very low budget, competitive with quotations from design-and-build contractors who offered cheap standard solutions. The over cost of energy-saving measures had thus to be kept to a minimum.

It was therefore decided to opt for high thermal insulation (100 mm of polystyrene on the roof and 80 mm of glass fibre to the walls with double glazing to all windows), a minimum volume for the building, and a high internal thermal mass.

Just as a temperature gradient exists within a structural element, a dewpoint gradient depending on the water vapour diffusion properties of the element exists too. If at any point in the structure the actual temperature is below the dew point then condensation will occur at that point.

Table A 3.1 gives some typical values of vapour resistance and thermal and vapour resistivities (thermal resistivity is the reciprocal of thermal conductivity – see Table A 2.3).

With more and more insulation being used, the designer must remember to consider both the thermal and vapour properties he or she is specifying. This is particularly true since some very good thermal insulants, for example glass fibre, are also very permeable to water vapour.

Let us now return in Fig. A 3.1 to the wall construction of Fig. A 2.1 and using the standard BRE procedure assess whether there is a risk of interstitial condensation.

The authors have rendered a valuable service to the building industry by the preparation of this volume with its wealth of actually built, rather than projected, examples. The book is well and soundly written with its emphasis maintained from start to finish on their basic theme, the necessity for the use in buildings of energy in many forms and the increasing desirability of learning how to minimize the use of non-renewable forms of energy in meeting those essential needs. Directed primarily towards architects, builders and owners in the United Kingdom, and consequently written within the scope of SI units, the book will be helpful to all who plan to build in latitudes north of the 50th parallel, where winter heating is more important than summer cooling.

Proper ventilation and the admission of outdoor air under suitable circumstances are not neglected, however. Building design features which are recommended by the authors are liberally illustrated by photographs and drawings of residential, institutional and commercial structures which actually exist. The soundness of their recommendations has been verified in most cases by the first-hand knowledge of the authors. Many of the ‘Energy’ books which have appeared in recent years have dealt almost exclusively with non-renewable forms such as the wind and the sun. These are not neglected here but their applicability is subjected to careful and objective analysis, with the intent of giving guidance which is based upon knowledge and experience rather than upon enthusiasm alone. The reader may well divide the book into three sections.

Introduction

From the underfloor heating of the Romans to the microbore hydronic installations of today may seem a small way but the path has been circuitous and the neglect of innovation has contributed to squandered resources and lowered living standards. For example, Fig. 6.1 shows an invention which was on the market in the early 1900s but failed to receive the attention it merited. The design is similar to the National Coal Board's present series of room heaters with back boilers. (Current designs include the safeguards of a vent behind the back boiler and a makeup tank.)

Prior to the 1950s, domestic heating in the UK was provided principally by open fires. Then, with rising prosperity, cheaper energy in the form of imported oil and technical advances such as small glandless centrifugal pumps designed to circulate small quantities of water against relatively high heads, central heating began to be adopted. In the past 30 years the percentage of the housing stock with central heating supplied by oil, gas or other fuel, has increased from about three to 50.121 Electricity for space heating also gained in popularity with the introduction of underfloor heating and storage heaters charged with cheaper night-time electricity.

This wide range of conventional heating systems developed for traditional houses is generally also applicable to low-energy buildings.

Introduction

Water-supply and waste-disposal systems are related in two ways. Firstly, in the UK, WC (toilet) flushing consumes about 36.5 1/p d or roughly onethird of the average household water use. Secondly, the point of final waste disposal may also be a source of fresh water. About one-third of the public water supply is from rivers, yet 60% of the local-authority sewage discharges to these rivers do not comply with the recommended 20/30 standard. (The Royal Commission on Sewage Disposal (1898–1915) made recommendations which were later adopted on the quality of sewage effluents to be discharged to water courses. The maximum concentration of suspended solids was limited at 30 mg/1 and Biochemical Oxygen Demand (BOD) was limited to 20 mg/1 for a dilution of 1.8 with river water; the Biochemical Oxygen Demand is a measure of the oxygen consumed during the oxidation (stabilization) of organic matter by a mixed microbial population and under aerobic conditions.)

In this chapter we shall briefly deal with water-supply systems and in the following one with waste disposal. Chapter 11 gives some water (and energy) conservation measures.

Virtually all homes in the UK are connected to mains water supplies and are likely to be so in the foreseeable future since planning permission is extremely difficult to obtain for sites that are not serviced. This tends to concentrate development and one of the interests of a group like the Autarkic Housing Project was to study potential changes in land-use patterns if housing was not constrained by availability of mains servicing systems.

SUMMARY

Some societies

With these concepts in mind, we may now look briefly at a number of societies that differ strongly both in terms of the way they order space, and in terms of their spatial logic as social systems. Obviously, within the scope of this book, this cannot be an exhaustive exercise. All we can do at this stage is to take a number of well-known cases where authors have described spatial properties of societies in such a way that they can be transcribed into the concepts we have used. In doing so we are, of course, adding nothing to the findings of these authors. We are merely using their work to show that the arrangemental model can provide a means for moving from social commentaries to analysis of spatial form. We may begin with the two well-known ethnographies: Fortes on the Tallensi of Northern Ghana, who live in dispersed compounds; and Turner on the Ndembu of Northern Zambia, who live in small circular villages.

Tallensi compounds differ considerably in size and complexity, but always are based on a strong underlying model, which can be seen in the gamma map of the simpler of the two compounds shown in Fig. 131.