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Studies of residential energy use, solar-energy technology for building, and the requirements for implementing technology in the housing industry led to a project to develop a solar water heater for apartments. A design study for a specific apartment was used to establish a solar water-heater cost model which is based on plumbing contractor bids and manufacturer estimates. The cost model was used to size the system to minimize the annualized cost of hot water. The annualized cost of solar-assisted gas-energy water heating is found to be less expensive than electric water heating but more expensive than gas water heating. The feasibility of a natural gas utility supplying the auxiliary fuel is evaluated. It is estimated that gas-utilizing companies will find it profitable to offer solar water heating as part of a total energy service option or on a lease basis when the price of new base-load supplies of natural gas reaches $2·50–$3·00 per 106 Btu.

Residential solar energy applications can provide a significant fraction of the U.S. energy budget. However, to do so, they must be combined with other energy-conserving strategies and diffused rapidly throughout the housing industry. Discussed are the potential resistances to the diffusion of solar energy within the U.S. housing industry; implications for the application of residential solar energy are treated. Richard Schoen is an architect and faculty member of the University of California at Los Angeles' School of Architecture and Urban Planning. He is also a staff consultant to the Solar Energy Team at Caltech. An earlier version of this paper was prepared and delivered at the International Solar Energy Conference, “Le soleil au service de l'homme,” Paris, July 2–6, 1973.

The first integrated system providing heating and cooling to a building by use of solar energy has been designed and installed in a residential-type building at Colorado State University. Solar heated liquid supplies heat to air circulating in the building and to a lithium bromide absorption air conditioner. Service hot water is also provided. Approximately two-thirds of the heating and cooling loads are expected to be met by solar energy, the balance by natural gas. The paper contains details of design and principles of operation. A breakdown of actual costs of the equipment and its installation is also provided.

The ability of the planet Earth to sustain its ever-increasing population is discussed in terms of both food and energy. The pressure of rapidly increasing population puts demands upon the world's fuel reserves which are so tremendous that we must look for other sources of energy. The author reviews various ways by which solar energy has been used in the past. Methods of heating and cooling dwellings are discussed, and it is pointed out that one-third of our annual energy consumption is used for these purposes. It is in this field that solar energy is likely to make its most important contribution in the near future. Means of producing power by steam and other engines are described, and the need for “good old Yankee ingenuity” is stressed. Pumping water for irrigation and distillation of sea water are other fields in which solar energy has long been used and where new “break-throughs” are needed. Photoelectricity and photosynthesis also hold much promise. The development of methods by which fuels for automobiles can be produced from water, air, and sunlight is a field in which research would be most profitable. Much research is needed to bring these developments to the point of feasibility, but the rewards will be rich, and the solar energy is there for the taking.

Solar energy applications are examined from the point of view of their profit-making potential. The study is based on a consideration of the availability and characteristics of solar energy, the sources of profit in conventional energy sources, and the type of industry which could participate in the commercialization of solar energy. Solar equipment now being manufactured is of four types—water heaters, batteries, cookers, and toys and novelties. Three types of solar energy equipment now in the development stage are seen to have early commercialization prospects. The largest market during the present century will likely be residential heating and cooling systems. Technical or economic considerations will limit several applications such as commercial electricity from solar energy and capture and storage by photochemical means.

The use of solar energy, in most applications, is dependent primarily on economic considerations; solar energy can become an important energy source when the costs of its use become competitive with the costs of energy from other sources. The basic and usually most costly item of equipment for solar energy utilization is the collector, or solar heat exchanger, and the amortization of the first cost of this and associated equipment is the major cost of solar energy. In this paper, the probable economic feasibility of several solar applications is assessed by using the costs of energy from present sources as a basis for estimating upper limits on the first cost of solar heat exchangers and their associated equipment. For example, for space heating in temperate climates, heat exchanger costs would have to be in the range of $1–6 for solar heating to be competitive; this appears to be within an attainable range. Economic considerations have helped shape the development of the Wisconsin solar energy program, and studies of solar heat exchangers and their application to heating, cooling and power generation are briefly described.

Domestic demands account for about 40 per cent of total energy supplies in Sweden. This article reviews research by the Building Technology Division of the Swedish Royal Institute of Technology over many years into the thermal behaviour of houses. It highlights the importance of effective insulation and of solar heat gains in particular situations, entailing modifications to conventional design calculations.

The effects of prospective uses of direct solar energy for power production, saline-water distillation, refrigeration and air conditioning, water heating, crop drying, etc, on the prosperity of the developing countries are discussed. A “solar home” of the 21st Century fulfilling all its energy requirements from the sun is visualized. Finally the difficulties in the way of solar-energy utilization due to the economic limitations as compared with conventional fuels are analyzed and presented in detail. The results are presented in a graphical form for finding the solar collector area required for a specific application of solar energy under various conditions of solar insolation and solar machine efficiencies and to assess the economic feasibility of solar-energy utilization for different applications when the costs of fuel, solar collector, and machine fabrication materials are known.

W HEN compared with the solar-energy resources of countries in the tropics and sub-tropics those in Britain are somewhat meager. Long periods with dense cloud cover, associated with the prevalence of industrial smoke, discourage the development of equipment for the conversion of solar radiation into directly usable forms of power. Some work has been done (by Dr. H. Heywood and others) on solar water heating and it has been found possible to obtain useful supplies of hot water for domestic purposes and for the warming of a few swimming pools. A number of scientific workers

This article emphasizes the importance of a supply of energy for the improvement of living conditions in, and general development of, underdeveloped areas. The costs of importing energy, whether in electrical form or as fuels, is usually expensive for such areas because of their remoteness from bulk supplies with consequent high costs for transport. It is suggested that, to supply power to isolated communities scattered over a wide area and with a consequent low density of population, local sources of energy should be used. The most widely distributed local resources are wind, solar radiation, and organic waste materials. The methods of using these by means of equipment now under development are described, and the probable costs involved are also estimated. As a conclusion, the article outlines a possible scheme for the combination of local energy resources to supply all the energy needs of a community in an underdeveloped area.

A wide range of possible measures for the conservation of energy in buildings are reviewed. The survey is made in the context of the American situation and covers energy use in space heating and co...

From the daily data for global radiation, the value of the amortizement, the cost of the auxiliary power, and the cost of the unit area of absorber, it is possible to find the size of the absorber that will result in a minimum yearly cost. An example from Africa for the daily heating of 55 gal shows that after an initial outlay of $250 the yearly electricity bill is about $81.

An important field of utilization for solar energy in India is in small village industries, as a supplementary power source. The application of solar energy to the raising of water for irrigation and domestic purposes, to cooking and to power generation are here discussed briefly; and the concentration of sugar cane juice and palm juice examined in some detail. Results are tabulated for experiments on the evaporation of cane and palm juices conducted in the Laboratory and in the open fields, using solar concentrators with 9 in. square plane mirrors, designed by Gardner. Field experiments showed an efficiency of 30 per cent, but it should be possible to reach 50 per cent. The capital cost of the unit can be recovered in fuel savings within 3 seasons.

Of the many novel solar energy schemes being investigated in the United States, the Ocean Thermal Energy Conversion Concept, OTEC, appears to be the one most likely to put the U.S. on the road towards energy self-sufficiency in the shortest possible time. The paper will illustrate how a solar sea power plant will convert the thermal energy stored in the tropical oceans into electricity. The main emphasis will be on capital plant cost and energy cost. Comparison with conventional nuclear plants will be made based on cost, energy pay-back and development time.

The energy needs of our society are steadily increasing due to the increase in population and the desire for higher standards of living (the Gross National Product is a monototonic function of the energy consumed).1 The fuel supply is not sufficient to satisfy such needs in the future. First natural gas, then oil, will be in short supply and will force consumers to explore alternative resources. It is certain that current comfort conditioning with natural gas and oil must change to other forms of producing heat, such as using synthetic fuels, electricity using heat pumps, and solar energy. The latter has great attraction as nondepletable fuel; however, its intensity fluctuation and high first cost of the needed conversion equipment has prevented major use of solar energy.

The high cost of a solar energy collector has presented a stumbling block to the generation of large amounts of useful power from solar radiation. The present paper discusses attempts made to design an economically viable system of power generation using the surface of the tropical oceans as a solar collector, and the deep cold water as a heat sink. No new technology need be developed to make such a system technically feasible. Ingenuity is required, however, in envisioning methods of performing the various necessary functions of such a system at the lowest possible cost.If indeed such power systems have a high probability of being economically viable, a new energy economy is to be developed. The author indicates how physicists have the proper training to guide the development of such a new energy economy.

The present search for alternate forms of energy in the face of an ever-widening fuel crisis is beginning to take shape along many fronts. One of the most promising of the new technologies ? solar energy conversion ? has just been allocated $50 million for the 1975 fiscal year by the Nixon Administration. Considering that this amount is close to four times that of FY 1974, perhaps the years of eclipse in solar energy research funding are past. Current efforts of the National Science Foundation (NSF) are further evidence of the trend.