Civil Engineering Reference
In-Depth Information
Each of these climates requires a different building envelope approach. In a cold
climate, insulation with multiple high translucency membranes such as ETFE foil
pillow systems work well, particularly if the design incorporates a system for
condensation removal. In hot and dry zones which require summer solar shading,
mesh fabrics and adaptable solutions for temperature differentials between day and
night are essential. In hot/humid zones, solid fabrics for rain protection with protected
openings at fabric peaks for the movement of air (Venturi effect) are important. All
enclosed fabric structures, whether they are a series of woven fabrics or foils usually
require a minimum of two skins, with each additional skin providing additional
insulation values. Maximum R values of four can be reached with these tensile fabric
materials and even greater insulation can be reached with foil membranes with
multiple layers.
Since all these membranes have little mass, the designer is required to use the
building itself as a thermal sink and building solutions using radiant flooring and
mass slabs offer a conducive counterpoint to the lightweight roof system. The foil
system has capacity for variable shading technology and has turned indoor spaces
into environments that can control or dramatize the effects of the sun. To achieve this
dynamic shading, various positive and negative print patterns can be developed and
printed on the outer two layers of a three-layer system. The simple change of position
of the middle layer, either to the top or bottom of the system, can transform the
system's transparency. The range of transparency of the system is project specific and
is determined by the designer's intentions and building performance. This variable
condition can also be utilized to dynamically alter the thermal properties of the
system to the desired performance.
The naturally translucent properties of the fabric (between 0 for “blackout” fabric and
up to 96% for foil) allow the designer to eliminate the need for artificial lighting
during daylight hours, saving on lighting energy for the building. Daylighting under
white fabrics is commonly used for permanent architectural applications and creates a
very diffuse and balanced light. These features are favorable to applications such as
sports facilities, exhibit halls, transportation facilities and atriums. Because of the
wide range of translucencies, fabrics with translucency in excess of 20% can support
some plant growth underneath and those with translucency in excess of 40% allow
several types of grass to grow underneath. Table 8-1 below shows the relative
reflection and absorption rates for different fabrics and assemblies.
Search WWH ::
Custom Search