The fully glazed building is universally recognised as being truly modern and is therefore still a favourite among contemporary architects. But as far as energy-efficiency and the control of the internal climate are concerned it is also asking for trouble. Nevertheless, sometimes designing a glass building that combines efficient use of energy with a high degree of comfort and good working conditions, may seem possible and even remarkably easy, as this small office for a metal fabrication company demonstrates.
|
The building in the evening sunshine |
|
Combined cooling/heating cealing-panel |
 Fans at the corners of the façade cavity distribute the warm air |
The two-storey, steel frame structure has a compact, square plan (40x40 meters), a fully glazed envelope, glazed partition walls and a central atrium. Given the glass facades, heat loss through transmission is kept at a minimum by combining a large internal volume with a low proportion of external surface. Clear storey heights of 3.2 m. result in volumes of air which are so large that air-change rates can be kept low during unfavourable weather conditions. The fully glazed roof over the atrium can be raised and moved, thus enabling draught-free ventilation and night-time cooling in summer. With extensive planting and a pond, the atrium also contributes to a better internal climate in the form of an oxygen reservoir and an air humidifier.
The glass wall may be problematic as far as heat loss in concerned,
it also serves a purpose. Up to 40% of the total energy consumed in office
blocks is just for artificial lighting. Better use of daylight can save
a substantial amount of this energy and also capture solar radiation.
A double-skin facade acts as a climate buffer between the interior and
exterior. With the help of reflector and absorber louvres, vents, recirculation
fans in this 600 mm. cavity, the facade can react promptly to changing
weather conditions. Both the inner and the outer skin comprise of insulating
glass, the outer of fixed glazing, the inner skin of sliding doors which
allow for individually determining the local climate. Intake of fresh
air into the cavity is regulated by adjustable vents in the outer skin.
Two louvre elements, one suspended above the other, regulate incoming
light. The upper reflector and the lower absorber louvers can be independently
controlled. Each louvre is perforated, so vision is not impeded. At night
the lower louvres are rotated 180 degrees to reflect internal lighting
back into the building. When the outside temperature is low, the vents
in the outer skin are closed. Only on the side facing the sun does fresh
air enter the cavity to warm up the absorber louvres. This warm air is
then fed into the interior by fans located in the corners of the building.
In summer the louvres are closed. Convection currents within the cavity
create a stack effect; fresh air enters at ground level, rises and is
exhausted as waste heat through the upper vents.
With vents and sliding doors open, the lower temperatures in the night
can be used for cooling. The building is also cooled by means of solar
energy. An absorption heat pump is driven by hot water from solar collectors
whose maximum output is available exactly when cooling is needed. Cooling
is achieved via the underfloor heating system working in reverse and via
grid ceiling panels.
The building is equipped with a computer management system with some 250
sensors and over 1000 actuators providing the system with information
to react accordingly. The software is based on fuzzy logic, so the system
has the abillity to ‘learn’.
(This text makes use of extensive quotes from: H.W Krewinkel, ‘Glass Buildings’)
pv