MVHR

Literature on the in-situ performance evaluation of Mechanical Ventilation with Heat Recovery (MVHR) in low-carbon social housing suggests that they can maintain a healthy ventilation rate in bedrooms in the UK. However, issues with noise and draught have been reported frequently. These issues may affect the sleep quality of occupants and have a detrimental effect on health and wellbeing. This research aims to present a quantification of these issues by carrying out detailed monitoring and evaluation at two case study sites in Wales, UK.

Residential ventilation systems target in an energy efficient manner an indoor atmosphere fulfilling people’s desired comfort requirements with regard to CO2, temperature, and RH. However, the reach of an indoor atmosphere is not limited to comfort only. Ensuring a healthy indoor atmosphere reducing the risk of acute and chronic diseases caused by the inhaled air is also of importance. A number of elements contribute to indoor air pollution, such as: Volatile Organic Compounds (VOCs), infectious aerosols, and Particulate Matter (PM).

To achieve stringent energy objectives, new dwellings are subject to energy conservation measures including low air permeability and high levels of insulation. Mechanical Ventilation with Heat Recovery (MVHR) can be used to control the balance between energy efficiency and Indoor Air Quality (IAQ) in these buildings. This paper evaluates the effectiveness of the design and operational strategies adopted in a new development comprising two apartment blocks in East London.

Highly energy efficient buildings such as ones built to the Passive House standard, require a very airtight building envelope and the installation of a mechanical ventilation with heat recovery (MVHR). MVHR systems incorporate ambient air filters, which reduce the introduction of particulate matter (PM) from outdoor sources into the dwelling. However, indoor PM sources, e.g. cooking, can also contribute substantially to occupants’ exposure and need to be accounted for when designing ventilation or deriving recommendations for filter classes. 

This paper describes the findings and recommendations of a meta-study examining the actual in-use performance of whole-house mechanical ventilation heat recovery systems (MVHR) installed in 54 low energy dwellings in the UK, as part of a national research programme. The performance of the systems is assessed using monitored data on indoor air quality (temperature, relative humidity, CO2) and energy use, cross-related with actual experiences of operating these systems through resident surveys.

New homes currently being built within the UK all incorporate some type of ventilation system, the majority of which are of the fixed mechanical fan type. These generally come in three generic designs known as single room background ventilators, continuous mechanical systems and continuous mechanical systems with heat recovery. Installation, inspection and commissioning of these systems is covered by Building Regulations, and there are training schemes in place which allow individuals to become Competent Persons to undertake these tasks.

Both critical and optimistic claims have been made regarding the performance of heat recovery ventilation systems (HRVS) in dwellings. Such arguments are raised partly because two key aspects are not fully clarified, i.e. the performance criteria and the influence of uncertainties. In the current paper, an assessment method for HRVS considering the influence of uncertainties is described. This includes  adequate assessment criteria, the method of identifying the uncertainties, and the method of addressing the influence of such uncertainties.