Materials matter The New Karolinska Solna hospital in Stockholm, targeted both gold LEED certification and gold in the Swedish environmental standard Miljöbyggnad. According to Jörgen Pell, engineer at White Arkitekter, targets were achieved “... Mostly because of the materials we used.” This meant selecting suppliers who used materials with a high sustainability rating – and none of the project’s 12,000 doors could contain PVC. Doors have played a considerable role in making sure energy efficiency is present in every part of the hospital. For the main entrances, Pell and his team weighed up themerits of using a combination of sliding and revolving doors against two sets of sliding doors. They opted for the latter because it was a cost-efficient way of keeping the interior cool in the warmer summer months and retaining heat during the unforgiving chill of the Stockholm winter.