How to determine glass area and glass-quality

Three graphs: “Glass Area”, “Loss factor” and “Construction Type” are linked together by broken lines which shift together along the x- and y-axes. They allow an easy transfer of the selected values from diagram to the other. “Glass Area”: For the room defined under “Room” these curves show the relation between the glass area (0 to 1 means 0% to 100%), the glass quality and gamma. The formof these curves depend on the room selected and defined under “Room”, for this reason one must click on “Compute” anytime one changes the room parameters. “Loss Factor”: This graph shows the relation between the room parameters, the glass area and quality and the loss factor of the room. Because this factor is relevant for the heating and/or cooling power one always should select it as low as possible, especially if several options for the glazings are open. “Structure”: The structure determines together with the loss factor the time-constant and thus the thermal inertia of the room. For reasons of simplicity the storage capacity is classified in three categories with enough precision for this level of optimization: “light”: Typical wood structure. C = 200 kJ/m2K “mixed”: Mixed structure with concrete floor slabs and brick walls. C = 600 kJ/m2K “heavy”: All concrete structure. C = 1 MJ/m2K

The procedure:

Glass Area: With this diagram one selects appropriate glass areas and qualities (UG/g-value) to keep the gamma-value of a room at its best values: Glass Quality:Four windows (coloured fields) allow the selection of glass types from a list of available products: click on the arrow and scroll until one finds an appropriate combination. There is a fifth field where one can define one’s own combination, may be not yet available. Room: Fill in the room properties. Select now the best value of gamma from table 1 and shift the vertical broken line on it. Now you see the best glazing areas (in % of external surface) corresponding to this gamma value for the five glass qualities selected. Select one of them and shift the horizontal broken line to the intersection with this curve. “Loss Factor”: the horizontal line from the graph 1: Glass Area intersects with the five lines corresponding to the five selected glass qualities. The intersection with the line corresponding to the selected quality indicates the resulting loss factor on the abscissa, so shift the vertical broken line to this intersection. “Structure”: The continuation of the vertical broken line from “Loss Factor” continues to graph 3: “Structure”. There it intersects with the three curves for light, mixed and heavy structure. Select the curve corresponding to your structure and find on the ordinate the corresponding time-constant. This should be near to the best value from table 1, otherwise start a again with graph 1 and modify the area of glass and/or the glass qualities selected.