Before you buy anything, fix the free things. Practical reductions that need scheduling and discipline rather than investment.
Energy reduction projects tend to get framed around equipment, but the cheapest savings almost always come from behaviour and scheduling. Here are the measures we recommend before anyone spends money.
First, audit your overnight baseload. If your site is closed for twelve hours and consumption barely drops, something is running that should not be. This single check finds more waste than any other exercise.
Second, review heating and cooling schedules against actual occupancy. Systems commonly run an hour or more either side of need, and in many buildings heating and cooling are fighting each other in the same zone.
Third, check your available capacity if you are on a half hourly meter. Many sites pay for far more capacity than they ever draw, and reducing it is a paperwork exercise rather than a physical one.
Fourth, tighten refrigeration maintenance. Dirty condensers and worn door seals increase consumption steadily and invisibly.
Fifth, switch off rather than standby across IT and kitchen equipment. Sixth, review external and signage lighting timers seasonally. Seventh, check compressed air systems for leaks, which are common and expensive. Eighth, consolidate under used space rather than heating it. Ninth, make one person accountable for the energy budget so that drift is noticed early.
None of these require investment. All of them reduce the volume you need to buy at your next renewal.