Ventilation
Why Ventilate?
We need to ventilate our buildings for 3 main reasons:
In particular, we need to ensure that carbon dioxide levels (from occupants breathing, combustion in appliances such as cookers etc) do not build up to dangerous levels. In some buildings, radon gas levels may also need to be taken into account.
We need to keep humidity (from breathing, cooking and washing etc) within comfortable limits, and minimise the risk of it condensing on internal surfaces where it may cause problems such as mould growth or rotting of the building fabric. Also, it is important to avoid interstitial condensation.
Ventilation is covered in Part F of the building regulations.
Passive Ventilation Strategies
We need to ventilate our buildings for 3 main reasons:
- to maintain internal air quality
- to manage moisture
- to cool overheating buildings
In particular, we need to ensure that carbon dioxide levels (from occupants breathing, combustion in appliances such as cookers etc) do not build up to dangerous levels. In some buildings, radon gas levels may also need to be taken into account.
We need to keep humidity (from breathing, cooking and washing etc) within comfortable limits, and minimise the risk of it condensing on internal surfaces where it may cause problems such as mould growth or rotting of the building fabric. Also, it is important to avoid interstitial condensation.
Ventilation is covered in Part F of the building regulations.
Passive Ventilation Strategies
Active/mechanical ventilation Strategies
1. MVHR
Mechanical Ventilation with Heat Recovery: a whole-house system comprised of ducts, fans and a heat exchanger. It uses an electric fan to draw in fresh, cool air from outside and pass it though a heat exchanger to reclaim warmth from outgoing stale, warm air.
1. MVHR
Mechanical Ventilation with Heat Recovery: a whole-house system comprised of ducts, fans and a heat exchanger. It uses an electric fan to draw in fresh, cool air from outside and pass it though a heat exchanger to reclaim warmth from outgoing stale, warm air.
2. Single room heat recovery
Single room heat recovery units could be seen as being a miniture MVHR system.
Single room heat recovery units could be seen as being a miniture MVHR system.
However, the efficacy of single-room heat recovery units are contested by some. See below...
What strategies might be employed to ameliorate the problem outlined above?
Openings: Windows, Doors etc.
Doors & Windows
Doors and windows obviously provide important functions: doors allow us to enter and leave the building; windows admit natural light which is important for occupant wellbeing and allows us to minimise our artificial lighting energy use.
Doors and windows obviously provide important functions: doors allow us to enter and leave the building; windows admit natural light which is important for occupant wellbeing and allows us to minimise our artificial lighting energy use.
Windows also admit solar energy - solar gain - which helps to reduce our space heating demand. However, both windows and doors come with a thermal penalty as it is dfficult to insulate these elements as well as walls.
Even where highly efficient products (e.g. highly insulated doors, triple glazed windows) are specified, the detailing of the junctions between these openings and the main walls needs to be considered carefully to maintain airtightness and avoid thermal bridging.
Even where highly efficient products (e.g. highly insulated doors, triple glazed windows) are specified, the detailing of the junctions between these openings and the main walls needs to be considered carefully to maintain airtightness and avoid thermal bridging.
The case study below explains how some of these issues
were addressed at the Denby Dale
house.
Other openings: service Penetrations
Entry points for utilities such as gas mains, and holes for flue exhaust pipes need to penetrate what may be an otherwise well-insulated building fabric. These can be seen as a necessary evil, with some heat loss being inevitable. However, good detailing around the penetration can help to reduce an unnecessary degree of thermal bridging.
Security
Secured By Design is voluntary standard that seeks to reduce crime rates through a mixture of certified products (e.g. toughened glass, lockable glazing units, secure locks and ironmongery on doors), passive surveillance and defensible space. The website has an interactive guide to its design principles.
Entry points for utilities such as gas mains, and holes for flue exhaust pipes need to penetrate what may be an otherwise well-insulated building fabric. These can be seen as a necessary evil, with some heat loss being inevitable. However, good detailing around the penetration can help to reduce an unnecessary degree of thermal bridging.
Security
Secured By Design is voluntary standard that seeks to reduce crime rates through a mixture of certified products (e.g. toughened glass, lockable glazing units, secure locks and ironmongery on doors), passive surveillance and defensible space. The website has an interactive guide to its design principles.
