Estimation of Greenhouse Heat Losses

 P.B. Panagakis, F.S. Zazueta and R.A. Bucklin


 Introduction

 Energy expenditure for greenhouse heating becomes critical
because of the instability in prices and availability of fossil
fuels. Heating represents the largest energy expense in
traditional greenhouse operations and the required amount of
money depends on the climate, the condition of the structure and
the crops grown.
 The first step in an energy conservation program in
greenhouses, is to make an estimate of the heat losses from the
entire structure. If the estimated losses are large, conserva-
tion techniques can be used to reduce them.
 This program, GREENHOUSE, allows the computation of
conduction, infiltration and total heat losses from the following
types of greenhouses:

 1) Gable or curved greenhouses using one material for the
 wall.

 2) Gable or curved greenhouses using different materials
 for the lower and upper wall.

 3) Quonset greenhouses.


 Input Data

 The required input data vary slightly with the type of
greenhouse for which the heat losses are being estimated. For
each one of the three types mentioned above the input data are as
follows

1) Gable/curved greenhouse using a single material for the wall.

 The required data to estimate the heat losses in this type
of greenhouse (Figure 1) are:

 1.1) Wall height (H): This is the height of the greenhouse
 wall in feet.

 1.2) House width (W): This is the width of the greenhouse
 in feet.

 1.3) House length (L): This is the length of the greenhouse
 in feet.

 1.4) Rafter length (R): This is the length of the rafter in
 feet.