What’s the diagnosis? Prescribing a hospital’s pathway to net zero.

It was a bright February day, and the sun highlighted the dust motes dancing in the still air of the room. My Natural Power colleague and I opened drawer after drawer stuffed full of huge pieces of paper, liberating a faint but pleasant smell that sparked memories of libraries. Most of the drawings that we pulled out were A1 or A0 proportions, or some other size that pre-dated the adoption of the A-series in Britain in the 1960s and 1970s. The titles and some of the details on the drawings also hinted their age: “New Geriatric Ward”, “Sister’s Office”, “Dictation Cubicle 3”. There wasn’t a metric measurement unit in sight.

We’d spent a few hours earlier that day surveying the various heating systems that served different buildings, or groups of buildings, on this medium-sized hospital campus. Things were working alright, in the sense that the rooms that needed to be warm, were warm; air was flowing through the ventilation systems; the hot water was hot. However, we found some concerning inefficiencies that meant that much more energy was being consumed than needed to be to provide a healthy, comfortable indoor environment. And the source of that thermal energy? Almost 100% fossil fuel (natural gas) – so the carbon intensity of running the hospital was high.

Transitioning a complex site like that hospital to Net Zero operation will be a long and complicated process. In time, the Estates team will swap out some or all of the campus’ gas boilers for heat pumps that will generate heat with approximately a quarter or a fifth as much carbon (and becoming greener over time) – or perhaps they will be able to connect the site to a low-carbon district heating network which uses its own large-scale heat pumps located somewhere else in the city. But for this site, before either of those steps are possible, there is a lot of detailed, human-scale work to be done. Is that pump running in a sensible and load-dependent way? Is the temperature of the water flowing in that particular pipe hotter than it needs to be – and is the pipe big enough? Are there things that could be done to the fabric of a building to reduce the amount of heat that is lost through the windows, walls, roof or floor?

Without the drawings, 3D models and other digital information we might expect from a more modern hospital, we must answer these questions in more roundabout ways. We poke around in plantrooms and services trenches, pore over paper drawings, inspect building management system (BMS) screens (with some scepticism about the accuracy of the story they tell!), and – perhaps most importantly – we talk to the people who work with these buildings and systems every day. After all that detective work, we are ready to build the models and calculations that will ultimately give us a list of options that we can confidently present to our client as the first steps that they can take on their decarbonisation journey with their eye on the prize that is Net Zero.