Coronavirus Assessment of Ventilation with Timetabled Teaching Space to Reduce Risk Resulting from Covid-19

On 10 of August 2021, the Scottish Government updated the operational guidance for Universities, Colleges and Community Learning and Development (CLD) to support providers in the planning for and delivery of  academic year 2021-22. This covered guidance on ventilation as one of the Coronavirus (COVID-19) mitigation measures. 

On 11 of June 2021, the UK Government published the Scientific Advisory Group for Emergencies paper on the application of CO2 monitoring as an approach to managing ventilation to mitigate Covid transmission.

The HSE has also provided updated guidance.

In terms of the advice provided within these publications in respect of Covid-19 measures, this highlights the importance of providing adequate ventilation as this reduces the concentration of virus is in the air, which in turn helps reduce the risk from aerosol transmission.

Assessment of space

An assessment has been undertaken in respect of all teaching spaces currently timetabled for use during Semester 1. These rooms have been remodelled to take account of the University operating on the basis of one metre plus distancing. 

In the vast majority of cases, this has significantly reduced capacity from the normal occupancy capacity of the rooms. It's also been mandated by the University that the maximum class size within any teaching space is capped at 50 persons, and face coverings should be worn.

Implementation of measures

Following the implementation of the measures noted, further assessment was undertaken to identify the method of ventilation provided within each of our teaching spaces. In general, this will fall into one of three categories:

  1. the room is fitted with mechanical supply and extraction ventilation
  2. the room is supplied with natural ventilation i.e. openable windows
  3. the room is supplied with a combination of both mechanical and natural ventilation

Where mechanical ventilation systems are installed, the following actions have already been implemented:

  • air-handling units have been adjusted to allow these to operate on full fresh air with no air recirculation
  • the building management system controls have been adjusted to ensure that ventilation air handling units operate 24 hours. This ensures buildings are purged with fresh air before, during and after use

Natural ventilation

In rooms that use natural ventilation (openable windows) to provide fresh air, it's important that these are opened prior to the commencement of teaching to ensure that the potential build-up of CO2 levels due to occupancy is mitigated. The following are the key points for these rooms: 

  • cleaning staff will open windows each morning and it is the expectation that the last users of the room will close any that remain open at the end of the teaching day. Security staff will check for any open windows as part of their normal, regular checks
  • there's an increased security risk if windows are left open, and risk of damage should there be windy conditions that could result in windows being blown out causing injury to passers-by. As such, room users should take sensible precautions based on the conditions at the time

More information required 

Where further information was required regarding the method of ventilation provided, these rooms were surveyed in order to determine this.  The results of this review are as follows:

49% of teaching rooms

192 rooms (49%) have natural ventilation as their primary means of supplying fresh air. In terms of rooms served by windows, these are designed to comply with building regulations and be capable of providing 10 l/s per person. As such, given the other mitigations in place, these rooms are assessed as low risk.

46% of teaching rooms

179 rooms (46%) were identified as having mechanical supply and extraction ventilation that has been sized to accommodate the room being fully occupied. As such, given the other mitigations in place, these rooms are assessed as low risk.

5% of teaching rooms

18 rooms (5%) required further investigation:

  • McCance 464 (capacity under current restrictions of 11 people including lecturer) has extraction ventilation only. This room has been removed from use until sufficient additional ventilation measures can be explored
  • Of the remaining 17 rooms, 8 of these have occupancy at one metre plus distancing of a maximum of fewer than 10 persons. A review of these rooms has been completed with sufficient natural ventilation available in all rooms

Further mitigations

In the event of staff concerns on the ventilation within rooms (including non-teaching spaces), the following are the key points to note: 

  • Estates Services have purchased a number of calibrated portable CO2 room sensors that, while temporarily placed within a space, will provide an instantaneous display of the % CO2 level within the room:
    • the SAGE report states that “A consistent CO2 value < 800ppm (absolute value) is likely to indicate that a space is well ventilated but does not mean that an environment is risk free of COVID-19 risks. Sustained high CO2 values (>1500ppm) are likely to indicate overcrowding or poor ventilation and mitigating actions are likely to be required.  Many factors influence the level of CO2 measured in a space so monitors should be used as a broad guide to the environment rather than to define specific ‘safe’ thresholds”
    • the meters are able to accurately measure the levels of CO2 in the environment, providing a warning when the levels are above the recommended level, as well as measuring the temperature and humidity of the environment;
    • data can be exported to a computer quickly and easily to be able to compare the CO2 levels in different time intervals
    • it provides a temporal trend graph of the history of the measurement record
    • it is a portable device with a rechargeable battery with a run time of up to 14 hours between charging and is easy to transport and locate
    • these sensors would be placed in rooms on a temporary basis where quantitative information would be required regarding the CO2   Monitoring would take place during a day of normal use, with the sensor collected by Estates and the readings examined (note that no action is required by the users of the rooms)
    • CO2 variation within a space and positioning and accuracy of sensors can easily result in variations in measured values of 200ppm or greater. Therefore, CO2 concentrations between 800 and 1,000ppm are regarded as reasonable upper levels. Regular concentrations greater than 1,500ppm are indicative of poorly ventilated spaces and would require immediate mitigating actions, including but not limited to reduced occupancy, increased ventilation or the room to be removed from use
    • while staff can refer to the digital display at any time to determine the current CO2 concentration levels within the room and where required, choose to increase ventilation through opening more windows and/or the room door, we would recommend that the use of ‘spot’ readings are discouraged, given the potential variations in measurement that can occur during the day

Requests for meters should be routed through the Estates Helpdesk via the Estates Maintenance Services System (EMS). Estates Services will review each request, and take appropriate action.

Please refer to Estates Maintenance Services System for guidance.