As a designer, specifier or building owner, you will want to be sure that your smoke ventilation system will provide fire safety in all situations.
Design on paper versus the practical realities of construction
It is all very easy to design on paper a system that provides a certain duty and airflow, but this often does not take into consideration the practical aspects of constructing a building. There are some potential pitfalls to avoid to ensure that your smoke shaft or pressurisation system will function as intended.
The importance of taking the necessary time to test and commission correctly
At the end of a project there is usually a mad rush to complete everything, to commission and hand over. In our experience this can throw up a host of issues.
For a smoke shaft system, it is essential to pressure test the builders work smoke shaft prior to installation and commissioning of the ventilation equipment. The normal maximum acceptable leakage is 3.8m3/h/m2 at 50Pa. Meeting this limit ensures that the design extract rates can be achieved without oversizing the fans. At this stage there is usually time and access to deal with excess leakage and the remedies are generally pretty straightforward.
With a pressurisation system, there are two issues: firstly, such a system is inherently sensitive to air leakage from the whole stair core, and secondly pressure testing can only be carried out right at the end of the job, when the whole core is complete. In practice this means no pressure testing is done and it is left to the commissioning process for the pressurisation system to discover whether there is unacceptable leakage.
Two steps to avoid difficult, expensive and time consuming remedial work
- Check that the builder achieves the correct level of build quality. For example, penetrations need to be properly sealed; there should be no gaps in mortar joints; and there should be continuous sealing around plasterboard – even when hidden above false ceilings! There are rules on maintaining the integrity of fire resistant structures. Excess structural leakage is the main cause of problems in commissioning systems.
- Carry out correct commissioning with ample time allowed for it. Small changes to the finishes (such as carpets for instance) can affect the ability of the system to perform. Therefore final commissioning cannot be properly completed until all finishes are in place and the building is virtually ready for occupation, with all services, walls and doors in place. This is all the more reason for builders to get the build quality right, as resealing the construction at this stage can be difficult, expensive and time consuming – and no additional time is likely to become available.
12.30-13.30 GMT, Friday 14th October 2016
Join Me, from 12.30-13.30 GMT on Friday 14th October 2016 I presents a CIBSE CPD webinar on commissioning and maintaining smoke control systems.
Commissioning of building services, including smoke control systems, is vitally important to the safe and energy efficient operation of buildings but is not always carried out or carried out systematically. Likewise, effective maintenance is a key factor in ensuring that safety critical equipment such as smoke control systems will operate faultlessly when needed.
In this webinar we set out the steps to follow to properly commission and maintain such systems.
Whitepaper - Commissioning and maintaining smoke control systems
This whitepaper introduces the legislation and standards relating to the commissioning and maintenance of smoke control systems. It then moves on to look at commissioning and then finally at servicing and maintenance of such systems.
Conor Logan is Associate Technical Director of Colt UK, Smoke and Climate Control Division. Conor designs innovative smoke control and HVAC systems and is also Chairman of the Smoke Control Association.