Active cooling with ventilation Systems

Heat Recovery Systems in Northern Ireland
6th September 2019
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Active cooling with ventilation Systems

New homes must now meet with strict energy-efficiency standards, while millions of existing homes in the UK and Ireland, have energy-efficient glazing and high-functioning heating systems. A growing proportion of the housing stock is also benefiting from low-carbon energy production through decentralised systems and technologies such as photo-voltaic (PV) panels.

The risk of overheating

As we get better at building and retrofitting homes to prevent heat losses in the winter, we may inadvertently increase the risk of overheating in warmer months. Throw into that mix the likelihood that we face a future where the number of unusually hot summers soars as the climate changes, with more frequent and intense heatwaves, and the scale of the problem becomes all too clear. All the indications would suggest that temperatures will be above those referenced in the Government’s Housing Health and Safety Rating System (HHSRS); or beyond the thermal comfort limits recommended by professional bodies such as the Chartered Institution of Building Services Engineers (CIBSE).

A step in the right direction

Significantly, MPs approved a motion in May this year to declare an environment and climate emergency: a move that the trustees of the Royal Institute of British Architects’ (RIBA) have formally agreed to join, driving support for the UK government’s commitment to a 2050 net zero greenhouse gas emissions target.

That, however, is years away. With the continuing (and urgently needed) construction of further housing in dense cities, many more people could find they are living in properties that reach uncomfortable or excessive temperatures. How are they to cope?

Combining ventilation with active cooling techniques to combat such overheating is a must. That is why we have developed our Ventilation Cooling Hierarchy: seven steps to better ventilation and cooling, designed to deliver a low-carbon solution to overheating issues in residential properties. Here’s how it works, with examples of how that solution is delivered:

1. Purge ventilation

Acoustically treated inline extractor fans located in habitable rooms provide additional ventilation up to 4 ACH, in lieu of openable windows. These can be used in conjunction with MEV (Central Extract System) and Mechanical Ventilation with Heat Recovery (MVHR) systems.

Solution: Acoustic Induct Fan, with easy application in residential developments where windows cannot be opened, due to acoustic site issues, and a low running noise to reduce disturbance. Contains two-speed motors for variable control and airflow requirements

2. Oversized MVHR and radial ducting

Increased extract and supply rates (typically to around 2.5ACH) to provide purge requirements without the need for additional solutions. Radial ducting ensures a balanced system and reduces noise and leakage to maintain lower running speeds.

Solution: ComfoAir Q. Range of airflow performances, with excellent pressure handling to reduce installed noise levels. Constant volume motors to ensure the delivery of guaranteed installed performance. Zero leakage, low pressure ducting solution for reduced noise levels and continued airflow performance

3. True summer by-pass and passive cooling

Modulating bypass within an MVHR system constantly aims to improve the internal comfort temperature/humidity by allowing full/partial/no heat recovery, depending on conditions. Passive cooling can be activated, based on external conditions that can help maximise comfort in warmer months by boosting supply air rates.

Solution: ComfoAir Q. Filtered fresh supply air in bypass mode to prevent dust, debris and pollutants entering the house. Summer by-pass works to deliver comfort: open, close, or partially opened or closed, depending on internal versus external conditions and comfort factor – a true summer by-pass, without airflow reductions. Passive cooling via automatic increase in flow rate during favourable external conditions to rapidly bring in cooler external air.

4. Ground to air subsoil exchanger

Working in conjunction with the MVHR system, sealed ground loops and a water to air heat exchanger provide pre-heating in the winter and pre-cooling in the summer on the supply/intake air

Solution: ComfoFond. Ground closed loop system that works in conjunction with the MVHR Unit. Provides pre-heating during the winter and air tempering during the summer. Hygienic closed loop system to prevent water, dust ingress and avoid the need for maintenance of a collector of open air-to air-systems. Maintain a balanced ventilation rate down to -22°C external conditions.

5. Compressor chiller and enthalpy

Again, working in conjunction with the MVHR system, this provides 1.5KW active air tempering and dehumidification via refrigerant cycle. Enthalpy MVHR cell passively reduces humidity of incoming fresh air under favourable internal/external conditions.

Solution: ComfoCool + Enthalpy. 1.5kW cooling capacity, integrated with MVHR Unit (CAQ600) and ducting network. Easy and space-saving installation. Filtered fresh supply air, not recycled stale air. Controlled via the CAQ600s, including ComfoSense C, KNX, or ComfoControl app for IOS or Android.

6. Chilled water coil

Works in combination with a centralised chiller system to provide 2-6KW of cooling capacity via the supply air of a constant volume MVHR system

Solution: ComfoPost. De-humidification of filtered supply air via MVHR during peak conditions (water at 7°C). Complete control and setting of temperatures to improve the indoor climate. Good thermal and acoustic solution, no draughts or nuisance noise, when combined with the ComfoWell attenuator.

7. Radiant heating/conditioning & active dehumidification

Complete heating, cooling and ventilation strategy, providing active humidity control and scalable plaster board embedded ceiling cooling loops, using boiler, chilled water or heat pump.

Solution: Nest ceiling panels + ComfoDew + MVHR. Low temperature radiant ceiling system with dew point control. De-humidification of filtered supply air via MVHR, during peak conditions. Used in conjunction with MVHR for best results. Complete control and setting of temperature and humidity to create the perfect indoor climate. Optimal thermal and acoustic solution, no draughts or nuisance noise. Equal distribution of temperature for the entire room.

The fact that there appears to be a much greater and collective determination to tackle climate change is encouraging. And yet, as we see temperatures in the UK reach levels way beyond what we might regard as ‘normal’, and homes increasingly becoming ‘heat traps’, the need for Mechanical Ventilation with Heat Recovery (MVHR) systems, such as the Qelair range, has never been more pressing

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