Description
The more complex scientific processes in a research facility are, the more important the mechanical engineering and equipment of the building is. Just how vital the specific air supply for a research or technical building really is can be estimated when air-conditioning and ventilation systems fail. Together with the other technical service systems (heating, cooling, gas, pressurized air and power) it establishes the ”bodily functions” of a research building – its circulation, metabolism, and nervous system – which are essential for its proper operation and use.
Air-conditioning and ventilation systems provide the required environmental conditions for laboratory research as well as enabling the reproduction of results. They control temperature and air-humidity and carry off heat and toxic air-borne substances. In certain cases pressurisation (for instance for clean rooms) or suction in spaces with chemical, biological, or radioactive sources of danger are also requisite. Generally, all research buildings have to provide a pleasant working atmosphere and above all protect employees from contaminations through dangerous substances.
In addition to these functions, air-conditioning and ventilation systems enable modular laboratory layouts that can flexibly accommodate various scenarios of use without changing the entire system. This flexibility can be achieved by means of a primary horizontal trunk line that suits the building geometry. The overall energy consumption of the system can be drastically reduced with an operation according to demand, intelligent controlling, and energy recovery systems such as heat exchangers.
According to the individual research disciplines the layout of air-conditioning and ventilation systems focuses on the following functions:
Physical laboratories
Heat exhaust; large amounts of thermal output call for direct water cooling (examples: cooling of electron storage ring, BESSY II; fusion experiment, Max Planck Institute for Plasma Physics, Greifswald)
Chemical, pharmaceutical, and biological laboratories
Exhaust of toxic substances, over/low pressure, clean air (GMP/GLP)
Animal laboratories
Animal protection, sterility, constant temperature and air-humidity, improvement of animal housing
Clean room laboratories
Compliance with specific clean room standards; heat exhaust; constant temperature and air-humidity
Even this rough classification shows the great variety of issues air-conditioning and ventilation systems have to deal with. These issues have direct consequences for the building structure. In order to meet acoustic and energetic requirements, air-conditioning and ventilation ducts have to be relatively large. Furthermore, the air volumes needed for the individual laboratory types vary notably. This fact can be highlighted by two extreme examples:
Biological laboratory
Number of air-changes: 4 to 8 per hour
High-spec clean room (class 10, US standard)
Number of air-changes: approx. 360 per hour
Service areas have to be dimensioned and arranged in accordance with these requirements. If large air volumes have to be transported, air-handling unit and target area should be located next to each other. If air is distributed by means of the mentioned primary horizontal trunk lines, a fair number of risers should be installed to restrict duct dimensions and ensure a flexible and energy sufficient system. Fire protection regulations are also a considerable space factor since shafts connect different fire compartments. Hence, extra space is required for the installation of fire barriers as well as for maintenance and regular revisions.
A sufficiently generous spatial layout is of general importance for all components of the system that are regularly maintained and revised – in particular the central air-handling units. The respective areas for transport of equipment, maintenance works, and installation openings have to be planned carefully. The service layout can also be affected by the fact that maintenance staff may not be entitled to enter particular restricted laboratory or security areas. Based on the brief and the general design strategy it has to be decided at an early design stage whether service ducts should run in central or individual shafts. Crossing ducts should be avoided to restrict floor-to-floor heights to economical dimensions. Generally, there are two supply levels:
Primary supply lines
Primary shafts, electrical and other service supply
Secondary supply lines
Supply lines connecting to individual spaces
Exhaust air should be blown out at roof level to avoid short cuts between air-intake and exhaust and to prevent environmental nuisance. Air-intake should take place at first floor level and not at ground level as this incorporates the risk to suck in contaminated or polluted air.
Air-conditioning and ventilation systems play a fundamental part in the design and layout of a research building. To achieve an optimal result, functional requirements have to be discussed and put into question repeatedly. In order to develop a sustainable and user-friendly solution, all participants in the planning process – from consultants to planning authorities – have to work closely together from an early stage on.
Originally published in: Hardo Braun, Dieter Grömling, Research and Technology Buildings: A Design Manual, Birkhäuser, 2005.