I spent some time in the main Data Centre yesterday trying to fit grommets to prevent cold air leaking out of the under-floor plenum into the middle of cabinets.  It is very difficult to retrospectively fit these due to the cabinets either being fixed in place or having too much cabling or low-racked servers in the way.  I recommend you think carefully about this prior to purchase.

I managed to fit a few anyway and the difference in the hot aisle was remarkable – it was feeling cold at some points and now it feels uniformly hot – which dramatically improves the CRAH efficiency.  I still have to contain the hot and cold aisles in some way to improve airflow even more.  We have had a quote for ‘butchers curtains’ that can be cut to shape and fit around the cabinets – these can be very effective, though not pretty.  Although the price is low (in relation to custom walled containment) it is still too high with our current budget limitations.  So we’ll have to see if we can finance this somehow after the refurbishment of our other Data Centre.