49 contracts in Heating, gas & mechanical run out between four and eighteen months from now. When they do, they get re-tendered.
A tender notice gives you three weeks' warning. A renewal date gives you months — enough to get the accreditation, speak to the buyer and prepare a bid that isn't rushed. The firm named on each row is the one holding it now.
Contracts expiring sooner than four months are left out on purpose: buyers re-tender well before the end date, so by then the opportunity has usually already been advertised and you are back to three weeks' notice.