The Code for Sustainable Homes is putting increasing pressure on contractors and installers to ‘build tight, ventilate right’, writes Charlie Bisby, projects director for EnviroVent.
In December, housing minister Margaret Beckett announced her proposals for making all new homes zero-carbon rated by 2016.
In order to meet these stringent new standards, developers are looking for more and more ways to increase their code star ratings, and getting the ventilation energy efficiency right is crucial to success.
Heat recovery systems are proving to be increasingly popular because of the fact that, as the insulation levels within dwellings increases under the code, there is a growing need for more ventilation to deal with the higher levels of CO2 and condensation. Heat recovery units provide constant, controlled ventilation to homes without increasing the heat loss normally caused by ventilation.
The best-performing products are also extremely energy efficient, reducing the calculated heat loss. What's more, if properly designed and installed, they can reduce the air changes while improving indoor air quality at up to 95% energy efficiency.
But the downside is that heat recovery systems can be the most complicated type of mechanical ventilation system to design and install because of the amount of ducting involved.
If you get it wrong, the penalties can be huge. Contractors and installers can face large claims if the systems they have installed do not meet the required ventilation rates through poor design or specification. Getting the design right must be a top priority.
The heat is on
A case in point is a new-build apartment block in Holborn, central London. Heat recovery was installed in every flat, but the systems were not working properly so the occupants complained to the developer.
Although a design had been completed for the system, it did not specify the correct size or type of ductwork to be installed, which was essential to the project. The occupants complained of poor ventilation, condensation and mould growth - all caused by the poor design.
The developer had to employ a manufacturer to solve the problem, which involved: a complete system redesign; ripping out and replacing the duct work; taking down the ceilings; reinstating the ceilings and redecorating.
Furthermore, the living conditions were so poor that residents were decamped to hotel accommodation for a number of weeks while the reinstallation work was carried out. Hundreds of thousands of pounds later, the developer had learned a memorable lesson: don't underestimate the importance of quality, bespoke design.
Surprisingly, some professionals in the housing business think they can get away with installing ventilation systems which don't have any form of design. It's likely that the contractor of a small, exclusive development of detached homes in Essex will not make this mistake again.
The heat recovery unit selected for his houses are one of the most energy-efficient Mechanical Ventilation with Heat Recovery (MVHR) systems on the market, but it was undersized for the house type. Because there was no system design, the ductwork used by the contractor was not the correct size or type, which resulted in numerous issues. As with Holborn, the Essex occupants complained of poor ventilation, condensation and mould growth.
A manufacturer who provided thorough system design was brought in and had to rectify the problem, ensuring that the right units were installed and the design was suitable for the properties. After many months and additional, unnecessary expenditure, the
ventilation problems were solved.
Getting it right
To make sure you don't fall into a similar trap, save yourself the headache and use a manufacturer that offers a dedicated design service. They'll be able to advise you on the most suitable product and ensure that an effective, correctly specified design meets the government's required ventilation rates.
And getting it right needn't be expensive. Some manufacturers, such as EnviroVent, offer contractors and installers a free design service and technical support, plus a detailed quotation, technical specification, supply of materials direct, on-site support and training and commissioning of the systems. You can use them for as much or as little as you need.
Choosing a system
EnviroVent has a range of MVHR products that have been tested by BRE and are included in the Appendix Q database. Its two new product ranges - HRQ and energiVent Q - are guaranteed to last the lifetime of a property, and like all its products, have been designed to have minimum impact on the environment.
The HRQ range of high-efficiency MVHR units provide constant, controlled ventilation to homes without increasing the heat loss normally caused by ventilation. Stale moist air will be continually extracted from the wet rooms, traditionally the kitchen, utility room and cloakroom areas, and ducted to the central MVHR unit.
The EnergiVent Q is a range of eco-friendly whole-house heat recovery systems that bring energy efficiency, innovation and performance to a new level. Available in two versions - the EnergiVent Q Air Source and EnergiVent Q solar - the systems are ideal for new build construction and energy-conscious refurbishment programmes.
Using Ultra Low Watt DC motor technology, these products are designed to match the life cycle of the property and are EnergiVent Q Air Source SAP eligible. They have a vapour-tracking function, optional wireless controls and an energy-saving zone control.
For further information telephone 01423 810810 or visit
www.envirovent.com