That's an eye-catchingly large number, being the amount of I&L space that Knight Frank's research shows will fail to reach the minimum EPC rating of 'B' that is expected to be a legal requirement in 2030.  

Although there are MEES exemptions that might apply to a sub-standard building, doing nothing is not really an option. At a time when borrowing is so much more expensive than in the recent past, significant capex may be needed from landlords to make their assets leasable and financeable. The falls in capital values make such spending even more painful for investors. However, there is potential upside to the risk: premium rents for buildings that tick the right sustainability boxes. 

The issue of EPC ratings and MEES fits into the wider refit/rebuild debate, about which Maples Teesdale and Realty Insurances recently hosted a presentation and discussion event: 
https://www.maplesteesdale.co.uk/events/back-to-the-future/