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Figure 3.27 Correlation between the Form Factor and U value
from Sustainable Design
by generaskopje
Correlation between the U value and the Form Factor
In the Figure below the corellation between the U-value vs Heat Loss Form Factor is shown.
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In the cases where the Form Factor is more than 3, the U value doesnt change significantly. However, when the form factor is below 2.5, the changes in U values can be quie significant and exponential. This reflects to the concept of `superinsulating` the Passivhaus buildings which doesnt need bo always the case, but it should be calculated accordingly21 .
Figure 3.27Correlation between the Form Factor and U value[47]
Urban form
In that regard, layout for the urban block in the cities are proposed relative to the climate, where[45]:
In a cool environment the layout should protect the buildings from the cold wind. The buildings should be closely grouped to have less exposed surface to heat loss and spaced properly to utilize the benefit of the solar insolation for heating. This layout is so called, an insolated dense layout. In the temperate zone, the plans are open, having the possibilities for free arrangements, intertwining the nature and the buildings. In the hot-arid zone the buildings can be grouped together and with the gardens can provide shade and achieve defense in volume. The buildings can be organized around closed courtyards, which act as cooling wells. In the hot-humid areas the buildings can be freely elongated. Buildings can be separated in order to utilize the air movement.
