Smart thermostats are extremely diverse products with growing consumer appeal. All smart controls have the potential to deliver energy savings, but the diversity of products means some can offer greater benefits than others. Boiler Plus identifies and requires specific functionalities with proven benefits: load compensation, weather compensation, or automation combined with optimisation. Some of these functions are commonplace even in standard, non-smart thermostats, so it is reasonable to expect them in products that are presented as ‘cutting edge’. More basic smart controls are also likely to have the potential to offer benefits, but this remains unproven.