Non-domestic buildings are frequently characterised as resistant to top-down low-carbon and energy-efficiency policy. Complex relationships amongst building stakeholders are often blamed. “Middle actors”—professionals situated between policymakers and building users—can use their agency and capacity to facilitate energy and carbon decision-making from the “middle-out”. We use semi-structured interviews with expert middle actors working with schools and commercial offices, firstly, to explore their experience of energy and low-carbon decision-making in buildings and, secondly, to reflect on the evolution of middle actors’ role within it. Our exploratory findings suggest that a situated sensitivity to organisational “pressure points” can enhance middle actors’ agency and capacity to catalyse change. We find shifts in the ecology of the “middle”, as the UK’s Net Zero and Environmental, Social and Governance (ESG) agendas pull in new middle actors (such as the financial community) and issues (such as wellbeing and social value) to non-domestic buildings. These issues may work in reinforcing ways with organisational pressure points. Policy should capitalise on this impetus by looking beyond the physicality of individual buildings and engage with middle actors at a systemic level. This could create greater synergies with organisational concerns and strategies of building stakeholders.