Factsheet gives information on the design of the envelope house, criticism of the envelope design, an explanation of envelope performance, special construction details, new ideas for the envelope house and economics of the envelope.
Factsheet on the solar greenhouse, including an introduction to the design differences between solar and traditional greenhouses, and sections on the attached solar greenhouse, the role of conservation, solar greenhouse additions: zoning, siting the solar greenhouse, design of the solar greenhouse, framing, building permits, foundation and structure, glazing, thermal mass, heat transfer, summertime operation and cost and performance.
Air infiltration rates are important in determining greenhouse heating requirements. Design recommendations usually suggest one to two complete air exchanges per hour under calm conditions. Tests made in 10 commercial ranges showed no greenhouse in excess of one exchange per hour, with one as low as 0.34 per hour, and an average of 0.56. However, additional tests at CSU showed marked variation, depending upon greenhouse size and heating methods, as well as type of structure and outside wind velocity.
This is done by means of a fan pressing air into the interior of a not air-tight greenhouse. The amount of exchanged air is measured by equipping the fan with a wind tunnel, it is depending on the difference of pressure between the inside and outside of the greenhouse. The difference of pressure and the air exchange figures are applied to the natural conditions in the case of different air velocities.
The primary objective of this paper is to show the distribution of heat losses in prairie commercial greenhouses of various constructions and to suggest and test methods of energy saving. Seventy five percent of the total heat loss is through the roof of a glass greenhouse. This can be significantly reduced by adding an extra layer of polyethylene preferably in the area where lower lightlevels can be tolerated.
A Compact Equipment for Survey of Air Renewal (CESAR) was developed at the Ecole Polytechnique Federale de Lausanne in Switzerland. Controlled by a microcomputer, this apparatus uses tracer gas methods ( decay, continuous flow or constant concentration). Up to ten different locations in inhabited rooms can be monitored simultaneously over extended periods of time, using mainly the "constant concentration" technique. Several air renewal surveys were carried out on different inhabited buildings.
Instruments full-scale agricultural and horticultural buildings with surface pressure sensors to measure wind loads under natural wind conditions. To show the effect of building geometry on wind loads, presents results of pressure coefficients on a selection of these buildings. The results in this report relate to transverse wind direction only. Shows that wind load does not reduce to a function of the geometric variables of height/span and roof pitch.
The structural design of glasshouses must provide for safety from wind damage while permitting maximum light transmission to the crop. A literature review of codes of practice, recommendations and data concerning wind loads on buildings showed several different procedures for describing the wind speed near the ground and predicting design pressures on low profile buildings.
Describes apparatus used to measure full-scale wind loads on a glasshouse. Wind pressure was sensed by a Dines anemometer and the variation in wind velocity with height by a small pressure tube anemometer. Wind loads on the glasshouse were sensed by pressure tapping points connected in sequence to micromanometers. Describes apparatus for the recording and analysis of data. States apparatus has been used for two years and found to be reliable in operation.
Reports pressure measurements made on five shapes of glasshouses, under natural wind conditions and generally over a 90 deg. range of direction. Gives pressure coefficients from 48 tapping points for four different glasshouses.
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