Below are details of three different commercial solar water heating systems,

AES passive solar systems are an affordable manufactured system. According to their own marketing material, if you have a high continuous demand for hot water, significant (payback over just 2 years) savings can be made by investing in this product, it is sensible to include them as part of a system which has another (usually gas or electric) source of energy to heat the water, as this means that the system is complementing rather than being soley relied upon, thereby ensuring that hot water is always available. AES ltd, Freepost, the Park, Findhorn Bay, Forres IV36 0TZ 01309 690132 f 690933

Thermomax are a brand of evacuated heat tube solar collectors

These type of solar collector are very efficient and will continue to work at below 0c. I have been told that they sometimes crack, being made of glass but they are guaranteed. The sun's energy is transferred through a collector plate within a low vacuum glass tube, to a heat exchanger. The collector plate has a conductive wavelengh selective coating, resulting in low radiation losses. The collectors also utilise infra red light which passes through clouds, a significant design advantage. The heat pipe which carries away the collected energy is highly conductive and heat never flows back into the collectors. Fluid inside the heat pipe evaporates when heated, flows to a condensor, gives up it's heat, then returns to the collector through gravity. Thermomax also make differential temperature controllers, with a microprocessor, which display temperature information, and accomodate maximum system efficiency. They are easy to install and very efficient, though you guessed it, expensive.

Thermomax, (01344) 874 747, f 872 030, Rayotec, London rd. Sunningdale, Berks. SL5 0DJ

NEW PRODUCT

Energie Solaire flat plate heat-exchanger applications and the Cenergia combined low and solar energy design in Edebjerggard, Denmark.

Founded in 1973, Energy Solaire S.A. is a swiss company specializing in solar technology. They have recently developed two new applications for their flat plate heat-exchanger; a solar application, the unglazed collector and an indoor application, the radiating panel. It took nine years to develop this technology with the aim of creating an absorber which could have a very low thermal inertia, be of industrial quality through automated production and have an exposed surface with a coating which increased it's efficiency. The absorber is a patented design made of two stamped and welded stainless steel plates. The cavities within the absorber give a contact area of 97% and the fluid is obliged to divide into many successive thin jets resulting in what they describe as perfect irrigation of the absorber, the heat transfer coefficient is 0.94. The selective coating used has a very low emmissivity of <20%, this produces a good yield and a low operational threshold. The surface area can be reduced by 10% or more compared to a 'standard' painted absorber. These types of absorber are ideal for applications such as swimming pool heating, water heating or preheating and seasonal heat storage.

Plane heat exchangers as radiating panels

Employed as a large radiating surface the plane heat exchanger offers particularly good cooling and heating properties, as in the solar application where the sheet can be used as roofing material when applied to radiating uses it can also function as a wall or false ceiling. The plane heat exchanger can also be used for energy recovery from air or water.

Cenergia

Skotteparken in Egebjerggard, Ballerup is an EU Thermie supported experimental building with 100 solar heating low energy dwellings, where the aim is to reduce gas consumption for heating and domestic hot water to 60% compared with 'normal' building projects and reduce the consumption of electricity and water. The basis for the project was that extra investments in energy saving measures of approximately 8% of normal building costs should correspond to savings on the life cycle cost of the building. In 1994 the Skotteparken project recieved "the world habitat award" for the introduction of ecology in housing with respect to energy and water use. It has also been chosen as the Danish best practice example for the U.N.Habitat II conference in Istanbul, based on this it has been chosen by the U.N. as one of the 100 best practice examples in the world. Following this Cenergia was the initiator and is energy coordinator of the 1993 EU Thermie project from the European Housing Ecology Network, where more than 600 solar low energy dwellings have been realised in 11 different housing projects in 7 EU countries. The building sector is responsible for approximately 40% of the total energy consumption in the EU and so creating a market for sustainable building in Europe is a logical strategy for the future, encouraging collaboration between local administrations, the building sector and energy specialists. Cenergia have a calculation programme called Optibuild, which combines calculations of energy savings with a price database on energy saving interventions, these are listed and presented as part of a solar low energy package solution according to their economy. A prototype CD ROM and brochure are available from Cenergia on request. ENERGIE SOLAIRE S.A. Ile Falcon-C.P.195 CH-3960 SIERRE ++41 27 55 22 12 CENERGIA Sct.Jacobsvej 4 2750 Ballerup, Denmark ++45 44 66 01 36