The quest for energy efficiency has led to very good insulation in residential buildings. While this is very good for the environment and electricity bills, it is having unintended consequences on stair lobbies, corridors and entrance halls, which tend to overheat. 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: use the smoke shafts already in place. These are typically positioned in a way that also provides effective environmental ventilation, so they can serve a dual purpose of evacuating smoke in case of fire and providing day-to-day ventilation.
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 the smoke control system for day-to-day ventilation
The simple solution is to use the ventilation equipment to provide smoke control to these areas. The Automatic Opening Vents (AOV) and shafts are usually positioned in a way that will also provide effective cross ventilation, so that potentially they can be used also to extract excess heat and stale air.
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 be readily configured to provide day-to-day ventilation without any additions.
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 smoke dampers between the stair and the corridor. 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 to prevent the heat from building up in the first place will also provide a more satisfactory result.
If you need more information on this topic, then we have some resources which you may find useful:
April 15, 12:30 PM
Join me as I present a free CIBSE CPD webinar on the ventilation solutions for overheated common corridors in apartment buildings.
This whitepaper discusses why the need for new ventilation approaches has arisen and how to make use of an existing smoke control system for day to day ventilation.
Paul Compton is Technical Director for Colt, experienced in smoke control, HVAC, solar shading and louvre systems.