We have welcomed the planned changes to Part F as they lay down the performance yardsticks that will be the framework of good ventilation practices for many years hence. They also give performance based guidance with suggestions on types of ventilation systems and quoted extraction rates.
The extraction rates are aimed at including the effects of air permeability, covered in other sections of the Building Regulations – this in turn should lead to healthier living standards and extending the working life of a home.
We believe that Part F will also promote innovation not only from manufacturers but also from the specifying and installation sectors of the industry as a whole. All facets have been consulted and the major trade bodies have been heavily involved in the consultation process – The Electrical Heating & Ventilating Association; Fan Manufacturers Association; Residential Ventilation Association.
It’s worth looking briefly at some of the details of the performance based guidance: new Part F, from a ventilation specifiers’ viewpoint, suggests what levels of performance are permissible. It gives the system designer a greater freedom of choice and allows him or her to work with a ventilation partner, such as Xpelair. We believe that Part F promotes the use of innovative products and solutions to satisfy and exceed the requirements. However, the new regulations do not dictate how this should be achieved……..
Of major importance to the specifier and installer is the section on ‘Installed Performance’. This means operational performance of a ventilation unit when it is actually installed. Performance needs to be quoted according to BS EN 13141 and the designer has responsibility to ensure that the ventilation unit(s)/hardware meet the requirement when in situ.
It aims to promote those manufacturing suppliers which have verifiable performance claims to their products – rather than those who may be described as being more optimistic when quoting performance data. The aim is to achieve a result which gives householders ventilation solutions that actually work.
So what are the types of ventilation systems covered in Part F? There are four distinct types:
1. Background ventilators with intermittent extract fans.
2. Continuous mechanical extract.
3. Continuous mechanical supply & extract with heat recovery.
4. Passive stack ventilation.
Xpelair is able to offer the system designer considerable choice in the breadth of range and number of options available. Solutions are available for bathroom, shower and utility rooms, kitchens and whole house systems. The Premier range offers centrifugal extract and condensation control options, whilst Xcell is the latest generation of mechanical whole house ventilation with heat recovery.
Ventilation must be controllable in order to maintain reasonable indoor air quality and avoid costly energy waste. Controls can be either manual or automatic and there are several methods, including; Humidistat (relative humidity); PIR (passive infra red); AQS (air quality sensor).
Part F 2006 has a more performance-based approach. It suggests to the designer what the desired levels of performance are – but it does not dictate to the letter how this should be achieved. Instead, it gives the designer freedom and promotes the application of innovative products and solutions.
Part F 2006 does this by recommending that the designer adopt one of three methods:
1. He/she can be guided by the specific indoor air quality levels which are quoted in Appendix A for relative humidity; nitrogen dioxide; carbon monoxide; volatile organic compounds and bio-effluence.
2. The designer can provide specific extract ventilation rates in the kitchen, bathroom and utility areas by using intermittent extract to specified levels.
3. The designer can adopt the document’s specific system guidance.
There is no doubt that the new Part F will make a huge contribution to improving the indoor air quality of Britain’s homes. And the industry does have the products to do the job.
One innovation is Mechanical Ventilation with Heat Recovery (MVHR) which allows indoor air quality to be sustained and levels of humidity reduced to below 70%. This drastically reduces the incidence of dust mites which cause asthma and other related breathing problems. Dampness and mould growth are also eliminated, preventing expensive damage to furnishings and the fabric of the property. The washable filters on the MVHR systems guarantee a cleaner indoor environment, making this form of ventilation ideal for brown field city centre housing developments – fresh air is possible, without having to open windows, conserving heat within the property and reducing potential household theft and security problems.
A distinct advantage of the MVHR system is its energy efficiency. Products are based around a heat recovery cell. These are extremely energy efficient and extract up to 90% of the heat which would otherwise be extracted through the ductwork to the outside of the property – these systems not only achieve high levels of indoor air quality, but they also have a role to play in the energy usage of the building.
Good system design is essential for a MVHR solution. This has been addressed by only a small number of innovative manufacturers. Xpelair for example has achieved this in two ways with its Xcell heat recovery units. Firstly, the company offers its ‘System X’ kits which contain all the necessary ducting components and accessories for different house types from a typical three bed semi to a five bedroom detached. Secondly, Xpelair provides a complete design service whereby the customer supplies details of the property in question and a detailed design is produced including all components. This is a huge advantage – being able to offer design expertise to house builders in particular – who may not have the in-house experience or knowledge necessary for successful MVHR installations.
To conclude, the new Building Regulations will progressively make homes more air-tight; requiring ever-less energy input to achieve the same comfort levels. And with escalating fuel costs, householders will resent losing any heat at all. Part F offers the specifier a number of ventilation options to achieve indoor air quality, but whole-house heat-recovery, or MVHR, systems offer the most energy savings. Correct specification, the installed performance of products and system design are essential. Only by taking into account all of these factors and by actively embracing them will the specifier achieve the aspirations of Part F and deliver cleaner air.