The ongoing quest for energy efficiency has led to very good insulation in residential buildings. This is very good for the environment and energy performance, but it also has an unintended consequence on stair lobbies, corridors and entrance halls, in the form of overheating. This results in unpleasant conditions for residents and possible issues maintaining cold water supply temperatures.
Heat build-up in corridors or lobbies of residential buildings is a common problem with a simple solution. If there is a risk of overheating in buildings where they already exist or are part of the design, use the smoke shafts. These are typically positioned in a way that can also provide effective environmental ventilation (the use of natural or mechanical ventilation to create better internal conditions). Therefore, they can serve a dual purpose of evacuating smoke in case of fire and providing day-to-day ventilation to extract any excess heat as required.
However, the design and controls need to be well thought through and there are some pitfalls to avoid for the solution to deal with overheating effectively.
Using a smoke control system to control overheating in corridors
The simple solution is to use the ventilation equipment that already provides smoke control in these areas. The Automatic Opening Vents (AOVs) and shafts are usually positioned in a way that will also provide effective cross ventilation - they can potentially be used to extract excess heat and stale air as well as providing smoke ventilation in the event of a fire.
More complex smoke control solutions have mechanical shafts serving multiple levels – ideal for ventilation of multiple floors.
Additional equipment or modifications
If your building has a multiple shaft smoke control system, it can possibly be readily configured to provide environmental ventilation without any major additions. In most cases however, control devices providing temperature and rain information is usually a minimum requirement.
Other more sophisticated additions include weathered ventilators to allow air in or out without permitting rain, time clocks, dedicated environmental fans, night-time purging systems and dedicated dampers for environmental control. Further enhancements can include air filtration, adiabatic cooling systems or recirculation type systems.
If, on the other hand, the building has a single shaft system, you will need inlet air. You could provide it from the stair, using a weathered roof smoke vent. In this case, you will need fire rated dampers between the stair and the corridor. However, this is not always an acceptable solution so you may need to consider alternative routes for providing a source of inlet air. You should also consider attenuation for the fans, as they will be running more often to provide day-to-day ventilation.
Controls and balancing the system
If all dampers open fully on all floors, then most of the ventilation will come from the upper levels with insufficient ventilation on the lower levels. Adding balancing dampers and a control system that can open either individual levels or banks of levels will prevent this from happening. Modulating the fans can increase or decrease the ventilation rate depending on the conditions in the corridors can also prevent the heat from building up in the first place which can provide a more satisfactory result.
If you need more information on this topic, download our whitepaper.
If you need a knowledgeable ventilation company to help you overcome overheating issues, talk to Colt’s team of experts today.
Conor Logan is Associate Technical Director of Colt UK, Smoke and Climate Control Division. Conor designs innovative smoke control and HVAC systems and was Chairman of the Smoke Control Association for over 9 years.