From our investigations of profitability we know that the heating cost is the highest or the next highest of all the production costs in most glasshouses crops. We, therefore, believe that heating investigations will possibly give the highest profitable result.

I believe that we are especially losing too much heat in the hours of darkness. We, in Denmark, have darkness 62% of the time in the winter half-year. 1st October-1st April. The plant-darkness certainly will show a longer period. We are using 75% of all the heat in the dark time, where we - if I may say so - do not need glasshouses.

We are building up a new place especially for a new series of heating experiments for reducing out-going radiation and for other investigations of the glasshouse climate. We are calling the place KLIMATION.

There are one operation house and 3 experiment houses, 2 of timber, 1 of aluminium. The 3 houses are all covered by glass. They are only of the dimensions 8 metres long, 3 metres wide to make it possible to heat by electricity. The house line is east/west and the distance between the houses is 2 metres. To prevent a differing influence on the last experiment house a glass gable is set up there. The base is made of timber: two layers, outside vertical, inside horizontal with a layer of roofpaper between.

To have a good control of the heat consumption we will heat by electricity. The system is based as usual on hot water pipes (5/4") and the water is heated in a specially built boiler with electric elements, giving 15 kw. Each house has its own boiler, which is about 70 cm long. The boilers are now controlled by electronic thermostats. The temperature of the boilers is controlled by safety-thermostats. The water is circulated by pumps, and we are going the untraditional way to the bottom of the system. We have in the expansion containers automatic control of the water level. We can heat to a 35°C difference of temperature. Each hour for each house we can print out the use of electricity by means of Sodeco printers.

To have room for inside placing of different protecting material we have hung up the heating pipes about 15 cm from the construction. It is wrong in most normal glasshouses, that the heating system is on the outside of, for example shading material. The space in this case will be maintained quite free of ventilation and other installations.

The air humidity will be controlled by hygrostats and regulated by means of mist nozzles, run by a magnetic valve. Measuring of the water will take place. The rainfall will be controlled to observe the influence on the glass and house temperature. For day-use of the houses the solar radiation will be measured by solarimeters and other lightmeasuring instruments.

The wind conditions will be given by instruments for wind direction and wind speed and for the toal wind run. The wind measurements will come in to a recorder. All other recordings will be printed on paperbands of a 24-chanel potentiometer recorder. Of course we hope that we shall one day be able to get help from an electronic computer.

I should be interested to hear your comments on the ideas.

CHRISTENSEN, SVEND AA. (1968). KLIMATION. Acta Hortic. 6, 258-259
DOI: 10.17660/ActaHortic.1968.6.21