Ventilation is an essential part of any home. We have never spoken about the 'V' word as much since the COVID Pandemic, but ultimately, we have ALWAYS needed ventilation which is essentially the removal of stale air and provision of fresher air to a home or building.
We now live in energy efficient time - it's about saving the planet and reducing our bills. So, we've done lots to our homes, new and existing to make them more air-tight. In the past, buildings relied on natural ventilation usually via opening windows and doors, airbricks and vents, and natural gaps/cracks in the structure of the building, but this is uncontrollable. Today mechanical ventilation systems ensure the movement of air, removal of stale air and introduction of new. You might not think it applies to your home but if you've added loft insulation, cavity wall insulation, double glazing or even built an extension, you have essentially sealed up your home!
The goals and benefits of ventilation in both existing and new homes is the same - ensures good indoor air quality! Need we say anymore?
Key aspects;
- prevents the build-up of excess levels of moisture from cooking, showering, hanging clothes to dry , boiling the kettle and breathing - which can lead to condensation, mould and can consequently result to health issues
- provides air for fuel-burning appliances, such as wood burners and gas cookers and stoves
- removes cooking smells
- helps remove pollutants, particles and other irritants inside your home and entering your home - pollen, pet dander, pollution, smoke etc
For homes there are 4 Key Methods of ventilating mechanically;
- Extractor Fans (there is a new type in town!)
- Mechanical Ventilation with Heat Recovery (MVHR)
- Mechanical Extract Ventilation (MEV)
- Positive Input Ventilation (PIV)
Extractor Fans - Which is the best bathroom fan?
Extractor fans aren't new - they've been around for a long while and offer a functional and practical solution for controlling excess humidity, smoke, heat removal or unwanted odours in wet rooms in your home - bathrooms, kitchen, utility and wc's.
A typical bathroom fan is 4" (100mm spigot) and kitchen fan 6" (150mm spigot) - the kitchen is larger due to Building Regulations requiring higher airflow rates.
It's not just about the size though. To choose the correct bathroom fan you need also to consider;
- Location - wall, window, ceiling or inline (inline is where the fan module site within the ducting so you just see the grille in the ceiling)
- Duct Run - The longer the ducting needs to be to get to outside (to remove all of the unwanted stale air), the more resistance it will provide, therefore you need to consider Axial (ideal for short duct runs up to 1.5 metres) or Centrifugual (ideal for longer duct runs up to 6m) so that the fan can actually do it's job
- Continuously running - The Air Shop recommend continuously running ventilation in all applications. Why? Because our homes need a constant refresh or air and air movement. We are sending 90% of our time indoors with all of our pollutant and moisture! Continously running fans aren't inefficient - they use low energy motors. Basically a continuously running fan runs at a constant trickle (you wont here it) and then boosts when it's needed via the light switch or humidity sensing (many other options too). And don't worry - they are very very very quiet!
- Safety Bathrooms and wet rooms are divided into zones, based on proximity to water sources. An industry standard, the IP rating, designates the zones in which any electrical fixtures or equipment can be installed. There are special requirements for extractor fans being sited in these zones. For example mains fans must be at least IPX4 rated and a 30mA RCD must be protecting the circuit. Alternatively SELV (safety Extra low voltage) fans can be fitted. Qualified electricians will ensure the correct type of fan and wiring is installed in accordance with IET wiring regulations.
For greatest effectiveness, your fan should be as far as possible from the source of replacement air (i.e. an internal door in a bathroom) and generally as high as possible.
Heat Recovery Ventilation (MVHR)
Mechanical Ventilation with Heat Recovery (MVHR) is a whole house ventilation system that both supplies and extracts air throughout a property whilst recovering and re-using heat that would have otherwise have been lost. Heat recovery is a ventilation system suitable for residential homes and is increasingly used to reduce the heating and cooling demands of buildings and ensure ventilation in where planning conditions around noise and air quality are in place and windows can't be opened.
Heat recovery systems typically recover between 60–95% of the heat in exhaust air (depending on the make and model) and have significantly improved the energy efficiency of buildings since 2010 when they first started being installed in larger volumes when detailed in the Building Regulations (Approved Document F System 4)
MVHR is suitable for;
- New build properties
- Full renovations - in order to reap the benefits of an MVHR System the fabric of the building needs to be insulated and airtight
- Where you require whole house ventilation solution
The Building Regulations currently requires an airtightness of approximately half an air change per hour, and as the airtightness improves, so does the requirement for continuously running whole house ventilation - it's always a balance between maintaining a healthy environment without the needless loss of too much heat.
How does it work?
The unit is installed in a cupboard, loft space or sometimes the ceiling void. It extracts and supplies air the home continuously. The extract fan extracts the stale, humid air from the wet rooms (bathrooms, kitchen, utility, etc). As it moves out of the home, it passes through a heat exhanger where heat is ‘recovered’. At the same time, supply air is being drawn in from outside. It is passed through filters (crucial!) and then passes it over the heat exchanger in order to temper it — and so supplies pre-tempered fresh air to all the living areas and bedrooms (heat retansfer doesn't happen in the summer to avoid overheating!)
MVHR Considerations
It is best to discuss your requirements with a specialist to ensure you have the right produt for your property;
- Accessibility for maintenance and servicing
- Sized correctly for the property including duct run calculations to avoid a small units having to run at a high speed which introduces noise
- Duct Type
- Controllability
- Filtration Grades
Positive Input Ventilation (PIV)
Positive Input Ventilation (PIV) work as a whole house ventilation system and create fresh and healthy living environments by supplying fresh, filtered air into a property at a continuous rate throughout.
PIV is required when:
- You don't want to do a full renovation.
- You require a whole house ventilation solution.
- You don't want to remove any walls or go back to brickwork.
Positive Input Ventilation (PIV) systems create fresh and healthy living environments by supplying fresh, filtered air into a property at a continuous rate throughout a property and is our most popular method of whole house ventilation.
Energy recovery ventilation systems provide a controlled way of ventilating a home while minimising energy loss. They reduce the costs of heating ventilated air in the winter by transferring heat from the warm inside exhaust air to the fresh (but cold) outside supply air.
Positive Input Ventilation (PIV) is a whole house air ventilation system that works by drawing in fresh, filtered air into a property from outside. These can be either installed in a loft space or on a wall in a flat or apartment. They ensure that a continuous supply of air is supplied into the home to eliminate or significantly reduce condensation.
The central unit draws air from either the loft or outside, filters it, and delivers it into the property, creating a positive pressure which, in turn, forces the stale air out.
New airtight homes are recommended to install a heat recovery ventilation system (MVHR) and not a positive ventilation unit (PIV). A positive ventilation unit works by pressurising the property and the contaminated air is pushed out through natural paths in the dwelling's facade or window trickle vents. If the property is built at or below 3 m3/hr/m2 air losses at a pressure of 50 Pa there would not be enough air leakage for the unit to work effectively.
Mehanical Extract Ventilation (MEV)
MEV is almost the opposite of PIV and is effectively a centrally situated fan that gently extracts stale or moist air from points of high humidity such as the bathroom or kitchen.
This creates a negative pressure, which theoretically draws fresh air evenly into the property through the envelope of the building.
MEV is required when:
✔ You are doing a full renovation or building a new house rather than a retrofit.
✔ You want an easy to install, whole house ventilation solution.
✔ You want a fit and forget solution.
Mechanical Extract Ventilation (MEV) refers to centralised systems which provide ventilation helping to reduce excess moisture using a multi point extract. MEV systems provide all year round good indoor air quality, protecting your home from condensation, damp and mould. Our MEV systems also come with a guarantee, giving you peace of mind when purchasing.
MEV or Mechanical Extract Ventilation are systems that provide continuous ventilation using multi point extracts. The centralised systems draw moisture-laden air from multiple wet rooms of a property. All our Mechanical Extract Ventilation (MEV) systems are reliable, long-lasting and operate at low noise levels.
Remember;
Every property is different and each property has their own ventilation requirements, what works for one won’t necessarily work for the next. It’s very important to ensure that you properly look into the different options, installing a whole house solution may seem daunting but it will also mean any damp or mould issues will no longer be a problem.