More than just a passing phase

Mechanical Ventilation with Heat Recovery (MVHR) has been an increasing feature in commercial buildings looking to install a ventilation solution. With specific targets set out on both UK and European levels, how can the adoption of PassivHaus approved technologies help companies meet these targets? Tunca Sekban of Airflow Developments explains.  

PassivHaus is often thought of as a specific building process that applies primarily to domestic properties; however it is a methodology that can apply to all buildings. The stringent requirements can be built into commercial spaces just as easily as they can with domestic buildings; the predominant consideration is the materials used. As yet the use of PassivHaus in commercial properties is in its infancy, however there is significant potential for any new commercial buildings to operate with almost no energy costs.

There are currently only seven commercial MVHR units in the UK market that have been fully tested and approved by the PassivHaus Institute – and four of these are Airflow’s Duplexvent MHVR systems. The testing procedure is strict; to be awarded certification a system must meet or exceed the following requirements:

  • High thermal efficiency (typically 75% or above)
  • Low SFP – under 0.45 W/m3/h (1.62 W/l/s)
  • A minimum requirement of G4 extract and F7 supply filters
  • Preheater assisted frost protection
  • Interior and exterior air leakage rates less than 3% of nominal air volume
  • Sound pressure level less than 35 dB(A)
  • At least three levels of speed control
  • Adjustable air volume with optional self balancing facility

Typically, most offices and commercial spaces are fitted with air conditioning units which are used to cool the air during the summer months rather than heat it when the temperature turns cooler. One of the biggest differences between MVHR and air conditioning units is that the air is not recycled so occupants will have a continual supply of fresh air.

This promotes a healthier environment with occupants less prone to sickness and sluggishness due to poor air quality. In a commercial space, the ventilation requirements vary depending on the application and also how many people the space is designed for. As a general rule the fresh air supply should be at least 30-36 m3/h per person.

Increasing pressure

In the UK, 98% of commercial buildings are at least five years old and their everyday use is equivalent of 90% of a building’s total emissions. In recent months, commercial buildings have faced increasing pressure to find ways to reduce their carbon emissions. It is no longer a novelty or a gimmick to install energy efficiency measures in a building, they are needed in order to help businesses survive energy price hikes and pressure from Government. Indeed, all new built commercial buildings will have to be constructed to a Carbon Zero level by 2019. Also, in the long term, it is likely that strong sustainability credentials will impact on the price of commercial property, with businesses shying away from poorly performing, energy hungry properties.

But it’s not just the rate of emissions that has placed increased pressure on finding new ways to reduce energy efficiency – the financial implications of increasing energy costs is also a major factor for building landlords, occupiers and developers.

Heating costs are one of the largest costs in the buildings hence utilising MVHR with high thermal efficiency (85%-90%) can save approximately 40% on heating costs – a significant figure for most companies. In commercial applications, this also reduces the average payback period of the MVHR unit from 7.5 years to three years against units with only 50% thermal efficiency, since the more air that is ventilated the more energy is consumed to heat this air volume.

Deliver on efficiency

By using a PassivHaus certified mechanical ventilation with heat recovery unit, businesses have the assurance that the product will deliver on efficiency and also provide a clean and healthy air supply that combats sick building syndrome. This recognised condition includes symptoms like irritation of the eyes, nose or throat and skin problems, with one of the key causes of this condition being poor air quality. To combat this, MVHR systems have a high efficiency, inbuilt filtration system to clean out airborne particulates and VOCs while preventing damp, stale air from posing any threat to occupants.

A PassivHaus approved unit has even more stringent stipulations for filters; requiring an F7 Grade air supply filter, which acts as a fine dust filter to further purify the air being supplied to occupants.  This in turn, promotes better and more efficient working as healthy air results in healthy occupants who are more able to work effectively. Efficiency can therefore be equated to more than just the fuel use of the building; it can also be used to enhance the work productivity levels of the people housed within the building on a day-to-day basis.

Furthermore, some MVHR units, such as the Duplexvent Flexi Range from Airflow, also feature intelligent controls incorporating an Internet server with service and user interfaces. With this unique feature a service technician can connect to the unit remotely, check the status, diagnose any faults (if there are any) and instruct the user what to do immediately, saving service and down-time to both technician and client.

Similarly the end-user benefits from this by monitoring the indoor temperature, CO2 and humidity levels and accordingly changing the ventilation parameters if necessary in order to maintain the optimum indoor air quality at all times.

Increased flexibility

This innovative system offers greatly increased flexibility over control, with users able to control the MVHR units remotely from laptops or smartphones. It also prevents users continually adjusting the output of the units – a common issue in workplaces and one that results in unnecessary, wasted electricity.

The performance of certified PassivHaus MVHR units can also be amplified by the use of zero leakage ducting. Semi-rigid ducting, like Airflex Pro from Airflow, offers increased ‘crushability’ and the ability to withstand higher external pressures, it’s also more hygienic with anti-static coatings limiting pollutants settling in the ductwork and therefore the instances of dust traps in the system.

The pressure is on to improve our existing commercial units and to create new ones that are as energy efficient as possible and MVHR units are witnessing an increase in popularity thanks to their ability to help reduce carbon emissions and to deliver over 90% heat recovery. Air that would normally be lost becomes a valuable resource to warm the fresh, filtered incoming air from outside to be distributed to the occupied areas of a building.

By using a PassivHaus certified MVHR unit in a commercial space both the users and the building owners can benefit from a healthier atmosphere and lower energy costs.

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