Carbon reduction is an issue high on the Government¡¯s agenda, but an existing low carbon top up heating solution is already available. John Kelly, Marketing Manager at Airflow, explains how mechanical ventilation with heat recovery fits in with a low carbon future.
There is a plethora of low carbon heating solutions currently available within the HVAC sector. The Government¡¯s definition of a low carbon technology encompasses everything from biomass boilers to air or ground source heat pumps. However, with all these technologies there are mixed reports as to their true carbon impact, leaving many end users confused about the real benefits they can gain – from such systems.
Also covered within this definition is mechanical ventilation with heat recovery (MVHR). Over the course of several years, these systems have become increasingly efficient thanks to investment in the technology of air-to-air heat exchangers and the low energy motors that drive them.
In modern homes, there is a real challenge to make the building as airtight as possible to reduce energy consumption, but still maintain a high level of air quality throughout. The average adult consumes 15,000 litres of air every day therefore a balanced, constant supply of fresh air is needed in the home This air then needs to be filtered, heated or cooled accordingly to retain a comfortable and healthy indoor environment
This is where an MVHR system comes to the fore, so much so that the Passive House standard insists on it to provide primary warm air to heat the dwelling when the air leakage of the structure is kept to an absolute minimum, typically under 1.5 m3/hr/m2.
Along with dwellings designed to the Code for Sustainable Homes, from level four and above, this standard is one of the major acknowledgements of the benefits of an MVHR system. This process heats no more air than required and reduces the overall heat loss as much as possible. Although UK interest is increasing in the Passive House standard, planning applications are still at relatively low levels. The first Passive louse conference was held in October this year. and hoped to shed more light on the building standard amongst UK builders and architects. However, the backing of such a robust European building standard has undoubtedly enhanced the reputation of MVHR and put it into a strong position as a heating solution for future generations.
As building methods change, and as old properties are renovated, another area which impacts on the efficiency of any MVHR unit is the installation and the ductwork used. Considering the fabric of the building and whether its design will present any installation problems, such as narrow cavities and small void space ¡ª as in a period property before specifying which ductwork is to be used, can stop a number of Situations arising. Badly fitted jointed plastic flat channel ductwork can be noisy and suffer from leakage which can result in lost efficiency issues, with the benefits of running of an MVHR system quickly disappearing.
However, there are now products on the market that eliminate these traditional ducting problems. For example, Semi-Rigid ducting, such as Airflex Pro, has an extremely high crushability rate, with some offering 16 kN/m2 ¡ª over double the minimum requirement of 8 kN/m2. Such small bore ducting systems are zero-leakage and this is why specifying this type of ducting can contribute greatly towards a lower SAP calculation for Dwelling Emission Rate.
This inclusion has a massive impact on the future of MVHR, as it allows specifiers and architects to design such ductwork into projects at early stages and for it to be included in their overall SAP calculation. When such efficient ductwork is then coupled with a highly efficient MVHR system, such as the Duplexvent DVI5O, the combined efficiencies are niaximised.
Plus such systems also meet current stipulations of Part I, of the Building regulations and will also likely meet the next set of revisions when they come into action in 2013. Increasingly, the regulations that are applicable to ventilation overlap One example is Putt B Fire Safety, which needs lobe considered for anyone using traditional steel ducting as it may cut across escape routes or fire cuffs. At the moment Part E, Resistance to the passage of sound, gives general advice on fan noise and air valves but as of 2013 it is likely there will be detailed sound breakout levels for these elements In fact, aside from the key Part F regulation, every one, apart from Part A, must be given some consideration.
The result is a Ventilation system that must meet a suite of regulations in order to comply with increasingly low-carbon and energy efficient buildings. This requires a high level of flexibility that other ventilation means do not have Taking into account the support of Passive House and the inclusion of MVHR into SAP, the market for and role of MVHR in future low-carbon building looks set to increase as we approach the target date of 2016 for a zero carbon new dwelling.
Category : BLOG &Uncategorized Posted on November 23, 2011