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A good lecture - ensuring design requirements are met in lecture theatresMarch 2014

A lecture may be interesting and informative, but if the lecture theatre is badly designed, with a poor sound system and a stuffy atmosphere, then even the most attentive student is likely to switch off and dream of the union bar. Building services engineers are well aware of the environmental conditions (temperature and humidity) that we need to enable us to be alert and perform at our best. Providing these conditions in every part of a banked lecture theatre that may be full or half-full of students is far from easy.

Temperature after 5 minutes

The building services engineer will provide the design for an air-conditioning system based on tried and tested design rules and personal experience. Unfortunately, no two lecture theatres are identical and there will always be some uncertainty over the effectiveness of the HVAC design. Flow simulation (CFD), when carried out by experts, can remove a lot of this uncertainty.

Recently, a leading design consultancy was asked to provide an HVAC system for a banked 400-seat lecture theatre. The challenge was to provide an environment between 20 and 23°C for all of the students for one hour when the theatre was full. The consultants sketched out a displacement ventilation system with air supplied through swirl diffusers under the seats and extracted through vents above the stage. The consultants then asked the flow modelling experts at BSRIA to simulate the air movement and temperature in the theatre and show whether the HVAC system would (or would not) meet the design requirements.

Temperature after 1 hour

The BSRIA experts created a time-accurate CFD model of the lecture theatre and simulated the environment in the theatre from the students entering the empty theatre to leaving the theatre one hour later. The team created a separate model of a swirl diffuser to ensure that the flow of cooling air into the theatre was replicated exactly.

The design consultants need not have worried. The simulation revealed an example of perfect displacement ventilation sustained over the one-hour period of occupancy (Figs. 1 and 2) easily complying with the design requirement. With BSRIA’s simulation, the consultants had the assurance they needed that the system would perform as required.

To learn more about the benefits of flow simulation, contact Jo Harris at BSRIA: or 01344 465586 or visit our Computer Modelling pages.

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