Energy and the Environment: Into the 1990s

By A. A. M. Sayigh

As the governments and peoples of the world come to face the global impact of the technological revolution, it is appropriate to consider the future of world energy supplies. This conference approached the task not only of developing the means of tapping renewable energy sources, but also of showing renewable energy to be a viable alternative to current, harmful sources of energy. Economic and educational problems were addressed along with the scientific ones. The development of alternative energy is of no use if it cannot be made economically viable or if people are not convinced of its advantages.

• Language: English
• Publisher: Elsevier Science
• Release date: Dec 2, 2012
• ISBN: 9780080983721

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PAPERS

PASSIVE AND LOW ENERGY ARCHITECTURE - FROM THE ENGINEERING VIEWPOINT

President. D S GILLINGHAM,     The Chartered Institution of Building Services Engineers Delta House, 222 Balham High Road, London SW12 9BS

ABSTRACT

The relevant achievements of engineers in the past are reviewed and the values of energy conservation measures are considered in relation to the costs of employment. Comparative powers of the components in building services are identified and approximate indications of their energy consumptions are given. The importance of efficient building design is emphasised and the possibilities for using non-depleting sources of energy in buildings are examined. Future developments in building services are discussed and the suggestion offered that architects of the future might care to assess the total amount of energy consumed by a building over its life, including the energy used in the manufacture, transport and site erection of the building materials, as well as the energy consumed by the services.

KEYWORDS

Efficient buildings

efficient services

energy sources

energy in building materials

PAST RECORD OF ENERGY CONSERVATION IN BUILDING SERVICES

Professional engineers engaged in the design, installation and commissioning of building services have not entirely neglected energy conservation in the past. It is probably not generally known that combined heat and power systems were being designed and installed as early as 1900, waste steam from the engines driving the electrical generators being used to heat nearby buildings. In the twenties and thirties district heating was extensively developed with the intention of economy in the use of energy - although ideas on the effectiveness of this have changed somewhat in the meantime. It is to be noted that, in the fifties, an advanced design for Shell Centre, in London, used the natural cooling capacity of the water in the river Thames to cool the building for much of the year. For many years before the first oil crisis in 1973 it was common practice for engineers to estimate the running costs of the heating installations they were designing and to recommend methods that could be adopted to minimise such costs. The practice of using an intermittent regime of operation for heating systems was developed and used as early as 1950. In principle, the same method is used today, even though it has been refined by the use of computer technology. The heat pump was also used, in both commercial and industrial applications, for many years before the world became acutely conscious of the finite nature of energy resources. More recently, detailed attention has been paid to the recovery of thermal energy from the exhaust airstreams leaving buildings and here also the techniques pre-date 1973.

The engineer is not a novice in the conservation of energy in buildings. As witness of this the enterprise of the CIBSE in producing a code for the efficient design and operation of the services in new and existing buildings (CIBSE, 1977, 1979, 1981, 1982) is to be noted.

THE ECONOMICS OF ENERGY CONSERVATION IN BUILDINGS

The prime concern of the user of a building in the mechanical and electrical services is capital cost. Money received at some time in the future, as a result of taking measures that will conserve energy, are of much less interest. This is often so even if a good economic case can be made. The reason for such a view can be seen if the annual costs of the services are compared with almost any commercial activity that is related to the use of the building. Table I provides such a comparison.

Table I

Comparative Costs of Heating, Ventilation and Air Conditioning. (Expressed in £/m² referred to the treated floor area).

The above analysis is based on the following data and assumptions:

Capital costs: up-to-date statistical average figures for jobs actually costed.

Heating: cased finned tube using low temperature hot water.

Ventilation: 5.2 litre/s over each m² of treated floor area, filtered and tempered, low velocity ducted supply and extract, with a recirculation facility.

Air Conditioning: four-pipe fan coil, with ducted auxiliary air.

Plant life: 20 years.

Maintenance costs: very approximate figures only (precise figures are not easy to obtain because of the considerable variation from job to job).

Natural gas: 40 p/therm.

Electricity costs: 6.1 p/kWh

Average staff salaries: £15,000 per annum.

Cost of employment: twice annual salary.

The electrical energy consumptions and costs are based on figures calculated for CIBSE Building Energy Code and relate to electrical energy consumed on site.

The figures suggest that, in terms of the value of possible annual savings, energy conservation may not always be readily accepted because the energy consumed (before conservation) represents only a small amount of money in comparison with the commercial or industrial activity. It follows that architects, structural engineers and building services engineers must engage in close co-operation. The design of buildings and their mechanical and electrical services must be developed in a way that promotes the conservation of energy without imposing penalties in capital costs. In this respect encouragement from central government through appropriate extensions to the Building Regulations, and perhaps in other respects, will be welcome.

REDUCING ENERGY CONSUMPTION IN BUILDING SERVICES

Efficient Building Design

This is a msot important first step: if the building is designed with energy conservation in mind then the duties of the mechanical and electrical services will be reduced and the energy consumed will be correspondingly smaller.

It is not enough to improve the insulating value of the envelope. This saves thermal energy but will increase the electrical energy used for artificial lighting if it involves an inadequate area of glazing. A proper balance should be struck between the benefit of natural lighting and the loss of heat through windows. Building services engineers can help by providing automatic control over electric lights to minimise unnecessary use, but the designer of the building can do more than this. Consideration must be given to the profile of the building, the location of the windows and the depth of the usable floor area in relation to the line of the windows, so that the utmost benefit can be obtained from natural lighting. Such steps will also help to give relief from overheating in warm summer weather by natural ventilation through open windows.

The building envelope must be tight, so that the leakage of unwanted air from outside can be eleminated. There are obvious adverse consequences if this preventa ventilation entirely: condensation is a risk and smells and other pollutants generated within a building must be diluted to an acceptable level by the admission of air from outside. Mechanical supply and extract ventilation, with heat recovery from the exhaust air, is then needed. A note of caution is necessary here. Mechanical ventilation alone is unable to prevent uncomfortably high temperatures within buildings, particularly if there are internal heat gains from lights and machines. Under such circumstances the windows must be openable in order to give relief to the occupants by the provision of adequate natural ventilation. If windows are not openable then air conditioning is required.

The mass of the building is important. With an intermittent heating regime the building should be lightweight to conserve energy but a massive building helps to smooth out temperature swings, especially in summer and particularly so for the topmost storey, where a heavy roof can reduce the impact of solar gains. Building mass, properly deployed, can be useful for storing unwanted solar heat gains for use at a later time when they can offset a heat loss. This is demonstrated by the many cases where Trombe walls have been used. (Todd, 1978); Keable, 1979).

The location of the thermal insulation in a building envelope is of great importance. When placed on the inside of the fabric it minimises the effect of the building mass and when placed on the exterior it increases the effect. In this connection, the position of a vapour barrier in the wall or roof, to prevent interstitial condensation, is critical in relation to the location of the insulation: the barrier must prevent vapour within the building from migrating to the colder parts of the structure.

Efficient building design and construction is essential if energy is to be conserved.

Conurbations and Earth Sheltered Buildings

In conurbations the mass of the buildings absorbs solar radiation during the day and releases it into the atmosphere later on. Each building has its own micro-climate and cities are warmer places than the surrounding countryside. In the middle of London mean annual air dry-bulb temperatures are 1.0°C to 1.5°C warmer than in nearby country areas on the same latitude (Chandler, 1965). Buildings in cities thus use less energy for heating than those in open country, other things being equal.

At 300 mm below the surface, records of earth temperature for Kew show a mean monthly minimum value of 0.6°C in January. The corresponding mean monthly air temperature is −5.6°C. Deeper down, the earth temperatures are warmer and the annual variation is less: roughly speaking, the mean earth temperature at a depth of 1200 mm varies from about 5.4°C in January to about 15.8°C in August. It follows that heat losses through the retaining walls and basement floors of buildings are less than through walls exposed to the outside air. There is extensive literature (Terman, 1981; Lane, 1981; Carmody and Derr, 1981) on this topic and there is no doubt that less energy is used for heating when earth protection is adopted for buildings, particularly in conjunction with a Trombe wall.

It is evident that there are limits to the use of earth-sheltering on a large scale. There are also health and condensation risks associated with any comparatively tight building, whether underground or not. Proper ventilation, natural or mechanical, is essential. Some rocks and soils emit significant quantities of radon gas with a resultant serious risk of cancer for the occupants of earth-sheltered buildings. Adequate ventilation is needed, preferably by mechanical means, because this can guarantee a specific rate of airflow whereas natural ventilation is not able to do so. A study of the risks, carried out in Australia (Baggs and Wong, 1987) implied that the provision of ventilation did not appear to be related to the concentration of radon and associated dangerous radioactive gases. Such a conclusion is not admissible because of the very heavy imprecise way in which the ventilation rates were measured.

Choice of Energy Source

There are practical issues that govern the choice of fuel but whichever energy source is chosen it must be economically justified over the expected life of the plant, the life of the source of energy itself and the lifetime of the building. There is the further matter of the rate of production of carbon dioxide and its contribution to the green house effect. Different fuels burn with different efficiencies and, because of their initial chemical composition, produce different proportions of carbon dioxide during combustion. At the present time natural gas appears to have the edge in terms of the production of carbon dioxide, cleanliness in combustion and resource life (Probert, 1986; Reid, 1988).

It is to be noted that, cost-effectiveness apart, the heat pump is a clean and efficient provider of thermal energy. Use is made of electricity (generated by whatever means) to transfer heat from cold external source to the interior of the building. This is achieved with an average seasonal multiplying factor applied to the energy used (coefficient of performance) of about 2.5, without any local pollution and without the use of much additional energy.

Non-depleting sources of energy should be subjected to economic analysis to justify their use even though there may be environmental pressures that appear to outweigh a cost-effective approach. National interests (such as, for example, the balance of payments) may be in conflict with environmental imperatives (Fells et al, 1978). Where these interests exist they are likely to prevail, in the short term, at the expense of longer term energy conservation.

The engineer must conclude that, over a potential 60-year life for a building, the source of energy used may have to be changed if energy is to be conserved. His design must therefore be flexible enough to accommodate this possibility.

THE ENERGY CONSUMED BY BUILDING SERVICES

The pattern of energy consumption in buildings varies according to the type of building and its use. As a generalisation, energy is used in commercial buildings for the following purposes: space heating, air heating, air cooling and dehumidification, air humidification, hot water services, lighting, small power, lifts and escalators, catering, fans, pumps and compressors. Computers make their own demands on services for cooling and consume energy in their own right. Industrial buildings consume energy in a manner related to their industrial function.

Energy economy in design and operation should be aimed, in the first place, at those services which use the most energy, in order to secure the greatest benefits and the best chance of achieving a cost-effective solution.

Assuming an office block that is heated and naturally ventilated, the typical approximate powers of the services using electrical energy are:

The lighting is assumed to be by polyphosphor tubes with efficient luminaires to give 500 lux. More than double this amount of electrical energy could be dissipated by the use of conventional fluorescent tubes in poorly selected luminaires.

Design requirements for heating and hot water services are likely to be about 40 W/m² and 13 W/m², respectively.

Energy conservation measures should aim, in the first place, at improving the efficiency of the lighting system: by designing the building to take advantage of natural lighting through windows, by a proper choice of tubes and luminaires, and by automatic switching for the lights. At the same time the thermal quality of the envelope should be improved. The hot water services might then be tackled by examining the cost-effectiveness of the use of solar energy, the recovery of waste heat, if any is available, and the use of spray taps. There scope for energy conservation.

In an air conditioned office building the maximum electrical powers depend on the type of system used but typical, approximate figures are as follows for a variable air volume system:

In the above example the power absorbed by the refigeration compressor is dominant but the lighting is close behind. The power absorbed by the main fans is also comparatively large. Major attention should be given to these three items during the design stage of the mechanical and electrical systems and also to their maintenance over the life of the system.

An analysis of the probable powers and duties of the components at an early stage in the development of the design of the systems will lead ultimately to effective energy conservation, if supported by competent installation, commissioning and maintenance.

At a first glance, small power would appear to be of little consequence but this is greatly misleading. Twenty five years ago an allowance of 5 W/m² might have been assumed with confidence. This is no longer the case. In a modern commercial office development less than 20 W/m² is unlikely and and figures of more than 70 W/m² have been used. The high figures represent the change in office procedures that have resulted from the advent of the computer: supplying power to multiple VDUs and other power-consuming items in common use is an essential service. The power required by computers has decreased over the years but more processing capability has been built into them, with the consequence that electrical powers have not reduced. Using more electronic equipment has meant that the power per unit floor area has increased.

COMMISSIONING AND MAINTENANCE

Systems aiming at energy conservation must be selected, designed and installed with commissioning in mind. Unless proper forethought is given to this they will be unable to fulfill their potential for efficient operation. The principles and practices recommended in the CIBSE Commissioning Codes should be followed (CIBSE, 1986).

It is necessary to allow enough time in the contract period to permit proper commissioning. This is particularly so when energy management systems are provided: the mechanical and electrical services must often by fully commissioned before the commissioning of the energy management system can start.

Without proper maintenance the aims of energy conservation will not be achieved. It should be regular, planned and pre-emptive, with safety of paramount importance. Adequate, but not excessive, instrumentation is necessary so that effective system operation can be supervised and ensured.

THE POSSIBILITIES OF USING RENEWABLE ENERGY IN BUILDING SERVICES

Solar Energy

A great deal of attention has been given to the use of solar energy for heating purposes, mostly for private houses at latitudes where there is a good deal more sunshine than commonly prevails in the UK. The records of energy conservation are generally good, heating being provided for much of the year together with adequate natural ventilation. In this country there has also been a significant measure of success, notably at Milton Keynes (Berry, 1989) although whether this is always so has been questioned in some instances (Owens et al, 1986); Evans, 1987).

The difficulties of applying solar energy to buildings in the UK are:

(1) The relatively low energy flux available. For example, the annual total radiation received in the South-East of this country is only about half that received in the Middle East.

(2) Storing the energy collected from the time it is provided by the sun until the time it is needed by the building. The results from a project in Wales (Todd, 1978) that provided solar heating for an old, comparatively massive building in a disused quarry, appear to show that 200 m³ of stored water is required to deal with a usable floor area of 200 m². The implications for a commercial building of even modest floor area seem to be formidable.

(3) The need for sophisticated equipment to produce heat transfer fluid temperatures above about 80°C.

(4) Conventional back-up heating plant is likely to be required in most cases, as well as the solar plant.

This is not to say that the use of solar energy is to be rejected. Conditions will change in the future. With higher energy prices and a longer term view by building users and developers on the economic worth of such conservation projects, their practicability for commercial and industrial applications may well improve.

In the past, a measure of success has been achieved in the UK for warming swimming pools and for pre-heating hot water services used for domestic purposes, but most cases do not stand up to a rigorous economic examination.

Wind Power

A good deal of energy is available in the wind but its successful use in a cost-effective way depends very much on the load factor. When supplying electrical energy to the national grid the factor is high and a case might also be made for institutional buildings, such as hospitals, that require electrical and thermal energy at all times. At the present, it appears unlikely that wind power can make a useful contribution to the energy needs of commercial or industrial buildings that are working for a conventional week of about 37 hours.

Combined Heat and Power

Here again the economic worth can only be established if the right conditions prevail (load factor, maximum electrical power needed, and the balance between electrical and thermal requirements). Good cases have been made in many instances in the past but these have always involved applications, such as large hospitals, where energy was needed for 24 hours in each day. Again it is unlikely that buildings with conventional five-day weeks and eight-hour days will be suitable.

FUTURE DEVELOPMENTS IN BUILDING SERVICES

History shows that progress in the improved performance of the electrical and mechanical services in buildings has been continual and this applies particularly to the effective conservation of energy. Current and future trends seem to be as follows:

Heat Recovery

Recovering heat from exhaust airstreams will continue to increase, particularly for institutional buildings such as hospitals and possibly also for industrial buildings. In commercial buildings cost-effectiveness will be the determinant. The use of phase-change materials for storing thermal energy may become more popular, particularly ice storage techniques for air conditioned buildings.

Refrigteration Plant

Air-cooled machines are likely to continue to displace water-cooled machines needing cooling towers for hygienic reasons, at the expense of some increased use of electrical energy.

CFCs will be phased out, for obvious reasons. This may well be coupled with better coefficients of performance and reduced energy consumptions.

Speed control and other developments in capacity variation will improve compressor performance.

Building Energy Management Systems

These will remain popular, provided that their use can be supported by services that are properly designed, installed and commissioned.

Computer Aided Design

Computers will be used increasaingly for design and costing purposes and, with the opportunities they present for more detailed examination of all the options, systems will use less energy and be operated more efficiently.

Fresh Air

Buildings that are mechanically ventilated or air conditioned will be provided with larger quantities of fresh air, as one step in the process of improving hygiene and comfort. As a consequence, the use of air-to-air heat recovery will increase.

Filtration

Better air filtration will be adopted for mechanical ventilation and air conditoning systems, again for hygienic reasons.

ADVICE TO YOUNG ARCHITECTS

If the presumption to give advice will be excused, it is suggested that architects should co-operate more fully with building services engineers, in order to achieve greater success in the conservation of energy.

Co-operation has been very good in the past but the suggestion here is that it should be extended beyond the provision of the obvious things, such as enough space for the plant, ducts and piping. There are two further matters to consider in this respect:

(1) Compliance with the Building Regulations and accommodating the services is not enough.

The building should be designed to minimise the design loads for the services.

The orientation should be chosen (if there is any choice) to exploit natural heating by solar gains through windows in winter.

External shading should be arranged to minimise unwanted solar gains in summer.

The windows should be selected and positioned so as to permit maximum advantage to be taken of natural light (if necessary, an atrium might be used, with appropriately controlled reflecting louvres, to assist this).

Consideration ought to be given to the provision of space for the storage of heating or cooling capacity, possibly as water, located in space that is of little first class use.

The mass of the building and the location of the insulation should be considered in detail to exploit any possible advantages.

(2) The materials chosen for building construction should be reviewed in relation to the energy used in their manufacture. A considerable amount of reserach has been devoted to this mater (Haseltine, 1975; Kohler, 1987) and it is evident that there are wide variations in the quantities of energy involved. As an example, reinforced concrete beams appear to need less energy for their manufacture, transport, and erection on site than do steel beams. Similarly, brick seems to be more economical than concrete, in terms of energy, and timber window frames better than aluminium.

There are other issues involved, of course, most notably capital cost and a hasty judgement would be unwise. Nevertheless, the total demand of a building for energy depends not just on the annual consumption of energy by the services but also on the energy used in the production of the building materials themselves. A proper audit should be carried out of the total energy required for the building and its services. One could assume a building life of 60 years and a services life of 20 years - implying that two system refurbishments will be needed in the lifetime of the building. Demolishing a building before its life is finished is wasteful in energy.

Targets (CIBSE, 1981) should be determined for the energy demands of buildings.

REFERENCES

Baggs, S A, Wong, CF. Survey of Radon in Australian Residences. Architectural Science Review. 1987; 30:11–22. March 1987

Berry, J (1989). Low Energy for Industry, Spectrum 7 at Milton Keynes. Architects’ Journal, 17 May 1989, 73–77.

Carmody, J, Derr, C. The Use of Underground Space in the Peoples’ Republic of China. Underground Space. 1982; 7:7–11.

Chandler, T.J.The Climate of London. Hutchinson & Co. (Publishers) Ltd., 1965.

CIBSE. (1977). Building Energy Code, Part 1, Guidance Towards Energy Conserving Design of Buildings and Services.

CIBSE. (1979). Building Energy Code Part 3, Guidance Towards Energy Conserving Operation of Buildings and Services.

CIBSE (1981). Building Energy Code, Part 2, Calculation of Energy Demand and Targets for the Design of New Buildings and Services, Section (a), Heated and Naturally Ventilated Buildings.

CIBSE (1982). Building Energy Code, Part 4, Consumption and Comparison with Targets for Existing Buildings and Services.

CIBSE (1986). Commissioning Code, Series A, Air distribution systems.

CIBSE (1986). Commissioning Code, Series B, Boiler plant.

CIBSE (1986). Commissioning Code, Series C, Automatic control systems.

CIBSE (1986). Commissioning Code, Series R, Refrigeration systems.

CIBSE (1986). Commissioning Code, Series W, Water distribution systems.

Evans, B. Saving Energy and Money? Houses at Milton Keynes. Architects’ Journal. 1987; 67–70. [18 February 1987].

Haseltine, B.A. (1975). Comparison of energy requirements for building materials and structures. The Structural Engineer, Sept.1975, No.9, 53, 357–365.

Keable, J. (1979). Understanding the Idea of Passive Solar Collection: Including the Primary Role of Thermal Storage, Conference (C19) at the Royal Institution, April 1979, ISES, UK Section.

Kohler, N. (1987). Global Energy Cost of Building Construction and Operation. IABSE Proceedings P-120/87, 193–204.

Lane, C.A. (1981). Earth-Sheltered Construction in Minnesota. Byggmaster, Dec. 1981, 60, No. 12, 34–37.

Owens, R, Nelson, G. A Heated Debate. Architects’ Journal. 1986; 38–39. 29 January 1986

Probert, W. R. Natural gas - current trends and future prospects. Energy World. 1986; 8–18. [January 1986, No. 132].

Reid, Bob. The Future Role for Oil in the Energy Spectrum. RSA Journal. 1988; 802–812. [October 1988].

Terman, M R. (1981). Energy Performance of an Earth-Sheltered Home with Trombe Walls. Underground Space, Nov/Dec, 1981. 180–185.

Todd, R W. (1978). A Solar Heating System with Interseasonal Storage. Conference (C15) at the Royal Intitution, May 1987, ISES, UK Section.

Renewable, Clean Energies Urgency - Solutions - Priorities

President CMDC and Chairman ISO/TC197 Gustav R. Grob,     Address of the author: CMDC and ICEC, Kellerweg 38, CH-8055 Zurich

Abstract

Climatiologists, environmentalists, biologists and medical doctors are reaching global consensus that the further growth of manmade pollution must stop, if future generations shall be given a chance to survive on this planet.Worries about acid rains, polluted rivers, lakes and seas, lung diseases and cancer caused by emissions from fossil fuels and chemicals are more and more overshadowed by the growing concern about the excessive carbon content in the atmosphere. What once was thought to be useful gases in the natural cycle are becoming a major threat to the global climatic balance: Carbon dioxide (CO2) and methane gas (CH4). The phenomenon of the Greenhouse Effect, causing an increasing atmospheric temperature, melting glaciers and ice caps, rising sea levels, thunderstorms, growing deserts - may soon climax in a climatic holocaust and the destruction of our life base.Never before in history the world community was faced with such a big challenge: getting the carbon inbalance under control by changing the global energy supply system, now made up by a frighteneing 75 % of fossil fuels and 14 % biomass, together producing 25 billon tons of CO2 per year. There is not much time left for experimentation. It might already be five minutes past twelve.What can be done to stop the emission of excess carbon that cannot be absorbed by the biosystem and the seas any more? Are the Toronto and Norwijk recommendations of a 20 % CO2-reduction by the year 2005 sufficient? Probably not, but the only sensible response to this double question is a double answer:

a -. Bring fossil fuel emissions down to a level that can be absorbed by the biosystem of this planet and

b -. increase carbon-absorbing plants to a level that can reduce the excess carbon content in the atmosphere in order to restore a sustainable climate and biobalance.

This paper will show what must and can be done to correct the most disastrous human mistake of this century - the overdependence on prime energies containig carbon. Practical renewable, clean energy solutions, their availability, cost and a timeframe for their fastest possible implementation will be given at the example of the combined electricity and hydrogen supply system SHEE TREE (Solar Hydrogen and Electric Energy - Trans European Enterprise). It will be complemented by a report about the new ISO committee on hydrogen energy TC197.

Introduction

To avoid catastrophic effects of fossil fuels on our environment and considering the climatic greenhouse phenomenon, causing constantly rising atmospheric temperatures due to excessive CO2-emissions, humankind is urged to replace polluting energies by renewable, clean energies. Exhibit 0 illustrates the alarming situation in which 94 % of all prime energies are hazardous and worsen the natural heat balance of our planet. Petroleum is contributing 32 %, coal 26 %, natural gas 17 %, biomass over 13 % and nuclear power 5 %. Hence about 90 % of all prime energies emit CO2 in various intensities, ranging from 60 kg per Gigajoule in the case of methane to 110 kg/GJ for wood.

At the conferences on the environment and climate change in Toronto, Norwijk and Bergen a reduction of the CO2-output of at least 20 % by the year 2005 was recommended. The marginal effect on the cumulative, exponential rise of CO2 since the turn of the century is shown in exhibit 00. Several scientists and politicians demand a much more drastic reduction for the rescue of our climatic balance.

Exhibit 000 shows the prime energy shares under the assumption, that biomass, natural gas and nuclear power output would remain constant over the next 15 years. Coal and petroleum would be reduced to the extent needed for a 20 % CO2-decrease till the year 2005. The result would be a steeper increase of hydrolelectric power than originally forecasted and a dramatic rise of other direct or indirect solar and geothermal energies. This model was based on the energy demand forecast of the 1989 World Energy Conference in Montreal, which might even be too conservative compared with recent predictions of the International Energy Agency/OECD of at least 3 % global increase per annum.

The frightening conclusion from this scenario is that the required total worldwide investment over the next 15 years into clean, renewable energy production would be in excess of 24’000 Billion Dollars, if an average investment of say 2000 Dollars per kWe and 5’000 hours average annual energy production would be assumed. This investment exceeds by far the sum of all world defence budgets - a task that will preoccupy capital markets and macro-economists to the limit of their