The challenge

A UK-based professional membership organisation was undertaking a major renovation of its London office, transforming approximately 510m² (5,500 ft²) of open-plan office space into a more flexible environment for employees, members and events.

As tenants in a multi-tenanted building, the company had limited control over the building's existing ventilation infrastructure. They therefore wanted a solution that could complement the existing ventilation system without requiring changes to the building infrastructure.

The redesigned space would include:

• Multiple meeting rooms available for members to use when visiting London
• Larger meeting and event spaces for company-hosted activities
• Renovated hot-desking areas
• New partitions to create spaces better suited to changing needs

The existing HVAC system had been designed around the original open-plan configuration. The larger open-plan hot-desking and meeting areas would continue to operate within this environment, but the introduction of partitions meant the space would now contain a number of smaller, enclosed rooms with different patterns of occupancy and use.

This change in layout was an important consideration for indoor air quality and air filtration. A ventilation strategy designed around a large open-plan area does not necessarily distribute air in the same way once that space is divided into smaller rooms. The company therefore wanted to add a layer of local air filtration that could work within the new layout and provide filtered clean air where people would be meeting, working and gathering.

There was also a wider objective. Following the pandemic, it was noticed that members were using the office less frequently. By creating comfortable, well-equipped spaces with enhanced air filtration, they hoped to encourage more members to return to the office for meetings, events and collaborative working.

Our approach

We began with an indoor air quality audit of the space, taking detailed room measurements and working with the Facilities team to understand the proposed renovation and how each area would be used.

The room dimensions and volumes were used alongside the clean air delivery rate (CADR) of the available filtration units to determine the appropriate number and size of units for each space.

The target was to provide the equivalent of 5 air changes per hour through filtered clean air. This allowed the filtration strategy to be sized according to the actual volume of each room rather than simply applying a standard number of units across the office.

Particular consideration was given to the newly created meeting rooms, as well as the larger meeting, event and open-plan areas. The aim was to provide effective HEPA filtration across the different spaces while maintaining a practical solution for a working office environment.

The solution

The final installation included:

• Air filtration units in every meeting room
• Multiple Blast units in the larger meeting and event spaces
• Additional filtration coverage across the open-plan and hot-desking areas

The units were selected and positioned according to the dimensions and intended use of each space, with the combined CADR sized to provide the target of 5 equivalent air changes per hour.

In the meeting rooms, individual filtration units provide dedicated local filtration. Room air is continually drawn through the HEPA filter, removing airborne particles before the filtered air is returned to the room.

In the larger meeting, event and open-plan areas, multiple Blast units provide the required clean air delivery for the larger room volumes and expected occupancy.

The units were also selected with the working environment in mind. Their low-noise operation makes them suitable for meeting rooms, events and day-to-day office use without becoming a distraction.

The result is a flexible filtration strategy that can work alongside the building's existing ventilation and adapt to the way the company’s newly renovated space is used.

Monitoring the results

Following installation, air quality monitoring was carried out to provide a snapshot of particulate levels with the building ventilation operating under normal conditions.

Baseline conditions were recorded first, followed by monitoring with the HEPA filtration active.

The monitoring showed a reduction in airborne particle concentrations, with the >0.5µm particle count reducing by 48% within the first five minutes and by 72% within the first hour.

For the >2.5µm particle count, the measured reduction was 6% within the first five minutes and 44% within the first hour.

The two particle size ranges were monitored using different instruments, so the results are presented as individual observations rather than as directly comparable measurements.

Overall, the monitoring showed a reduction in airborne particle concentrations following the introduction of HEPA air filtration.

Managing CO₂

Air filtration does not remove CO₂, so it does not replace the need for effective ventilation.

The company understands this distinction and continues to make use of meeting breaks and opening doors between sessions to help manage CO₂ levels, particularly when meeting rooms have been occupied for longer periods.

This means the two approaches serve different purposes: ventilation provides fresh air and helps manage CO₂, while HEPA filtration provides additional removal of airborne particles within the occupied spaces.

A practical approach to air quality

This project demonstrates how air filtration can provide a practical addition to an existing office environment when changes to the building infrastructure are not an option.

By carrying out an air quality audit, measuring the individual spaces and sizing the filtration around room volume and CADR, the solution was designed specifically for the way the renovated office would be used.

With filtration in every meeting room and additional capacity across the larger spaces, the company has been able to provide enhanced filtered air throughout its 510m² office while retaining the flexibility of its new layout.

The result is a more adaptable working environment designed to support employees, members and visitors, while giving the company greater control over the air filtration within the spaces it manages.