How to ventilate hospitals

How should hospitals of the future be ventilated?
30 March 2021

Interview with 

Alan Short, Clare Hall, Cambridge University


sun shining through a window with flowers in a vase


Cambridge University’s Alan Short is an architect who’s very interested in designing hospitals, and has done recent work on the flow of air in hospitals. He spoke to Chris Smith, who firstly put to Alan that Florence Nightingale might not feel out of place in the hospitals of today...

Alan - I'm not sure about that Chris! I'm looking at her 1858 Liverpool lecture, which changed hospital design in Britain, and she wrote 'Natural ventilation is the only means of procuring the Lifespring of the sick: fresh air”. No artificial ventilation can do that. And in the article there are plans of bad hospital wards, which are deep plan and can't be cross ventilated. And I think she'd see quite a number of those.

Chris - What I was getting at is that we don't do what Christine Moody was just saying, which is give people their own space and their own air and therefore their own opportunity to keep themselves away from the sources of infection that you see coming from, inevitably, contact with others. And what we probably need to be striving to do is to actually do that in order to keep people separated as much as possible, where appropriate, so that we don't get a cross spread of infection between patients, but also critically between staff and patients.

Alan - I was very interested to hear Christine say that because Professor Roger Ulrich came over from Texas A&M perhaps 12, 14 years ago, and persuaded the department of health that hospitals should be like hotels, where every patient has their own room, but there are quite interesting implications to that. Particularly the population of hospitals becoming older and older, people with dementia. We spent a lot of time in the Bradford Royal infirmary, which is a classic Nightingale Hospital, and the staff there were very pleased to have the older patients gathered in a Nightingale ward. And you can redesign them, make them much nicer and give everyone privacy. We have a zig-zag plan, which the cabinet office called Business Class for the NHS. So one can think a bit more laterally, I think.

Chris - Let's look at the ventilation for a second because that, arguably, is key isn't it, especially when you've got respiratory infections like Coronavirus, but also like the flu, which is a scourge every winter and things like Norovirus that causes winter vomiting disease, although that is not a respiratory infection air currents carry it round and lead to explosive outbreaks. How can we use ventilation to try to mitigate against some of those threats?

Alan - The enthusiasm for making artificial environments in large public buildings now is very problematic actually because mechanical air flow systems that push the air in at the top and take it out, mix and churn the air. That's part of the idea to save heating energy, but it's pretty disastrous in terms of spreading pathogens around a ward, or indeed in an operating theatre.

Chris - So how could we do it better?

Alan - You know, the NHS has to be zero carbon by 2050! We're very interested in reviving what was a fantastic art and science of natural ventilation. You can enhance that with some mechanical help, but our interest is in recovering all of this lost knowledge. And you can see it disappearing in the waves of hospital building since the last Nightingale hospitals were built in the late 1930s as matchboxes on muffins towers and other high rise slab buildings and so on become completely artificial in their environments. This is highly problematic and not really necessary, certainly not in England.

Chris - But what do you have in mind? What do you envisage would be the solution and how does your strategy work? And rather than just drop a cheque for 3.7 billion pounds and hope for the best, how do we do something that we know is going to be money well spent?

Alan - My colleagues and I have designed an imaginary very, very low carbon hospital for the department of health. They've set a target of 35 gigajoules to a hundred cubic meters and they didn't know whether you could make a hospital that would achieve that.

Chris - How does that compare and contrast with today then?

Alan - Addenbrooke's is about 104-107 gigajoules so it is a massive reduction in energy consumption. But we have a nice scheme for Addenbrookes, which is to stack ventilate all of the floors and to cross ventilate them, so organised natural ventilation. Of course a big problem in hospitals is they overheat in the summer and mechanical ventilation systems can't deal with that, and they have a much better chance of calming the environments if you naturally ventilate them.

Chris - Can you just explain to me how this actually works physically though? What would you have to employ? What would you have to install in order to have what you're envisaging actually working?

Alan - The most interesting scheme for the tower puts another elevation, a facade, on top of the one that's there, shades the windows because there's a huge solar gain problem, and it connects each floor to a series of stacks that go right up to the top of the building. And you just use the natural pressure differences, the top to the bottom of the building, to drive huge amounts of air through the building. And we've modelled that rather carefully and it looks very promising and this has really no energy at all expended in venting the hospital.


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