CBG Consultants were initially appointed to perform a ventilation assessment to help optimise thermal comfort and air quality within the main library at the London School of Economics (LSE).
The 20,000m2 building had been subject to a major refurbishment in 2001. However, at that time the library had a much lower occupancy rate than it does now, with advances in digitisation resulting in fewer book stacks and more people. Alongside the introduction of 24-hour opening times, a need to re-evaluate the building ventilation arose to ensure that any comfort issues resulting from the changes in occupancy could be minimised. As this is a learning environment, LSE were also keen to ensure that the air quality within the library would be maintained to as high a standard as possible.
CBG Consultants used the SketchUp plug-in to import the building geometry into IESVE. From there, they performed a calibration exercise through which data from CO2 loggers installed within the library and other BMS data was fed in to the virtual model for analysis. Information gathered from the client regarding building use and site surveys added further accuracy to the model calibration, helping to create a better overall understanding of how the building and ventilation was operating.
The building relied on a combination of stack ventilation, different types of actuated and manual windows, and some mechanical ventilation. This required complex modelling in IESVE but, using MacroFlo, CBG were able to simulate airflow through the building and provided recommendations to LSE on a solution that would be best suited to their requirements.
The client was impressed by the capabilities of the 3D calibrated model and were interested to explore other ways in which they could maximise its potential.
Analysis of occupant feedback revealed that a better staff and student experience could be achieved by meeting the following criteria:
The IESVE software was used to analyse a range of potential solutions including: adjustments to the BMS window actuator settings; centralised mechanical ventilation; local mechanical ventilation mixing boxes; increased window opening area; application of solar films to the windows; and peak cooling. Central mechanical ventilation combined with peak cooling was identified as the most suitable for the building.
Perhaps one of the most beneficial aspects for the client was the ability integrate the model with their maintenance work. Issues with the window actuators had proven to be one of the greatest burdens on the maintenance team at LSE. However, they discovered they could focus time and cost where it would have greatest effect, firstly by assessing the impact of each opening within the model and then prioritising repairs accordingly.
The IESVE model was also used to assess a number of “what if” scenarios. This considered a variety of factors including the shading impact of changes to the surrounding buildings, additional changes to building occupancy, and the effects of future climate change, to help determine strategies to futureproof the building more effectively.
“The whole exercise of digitising the building proved helpful for a lot of reasons. The great thing about this project was the level of engagement from the client. They realised that by investing a bit more time and effort in the model, they could open up a whole number of possibilities to support their asset management strategy and became much more efficient in their maintenance approach as a result.”
Senior Sustainability & Energy Engineer, CBG Consultants