Andy leads Human Nature’s Delivery Unit, which is tasked with ensuring the deliverability of the designs within the framework of Human Nature’s principles, beliefs and ethics. He talks to us about timber, electric excavators and the many benefits of hempcrete.
Hi Andy. Tell us about your background.
I’ve always been a carpenter, even as a kid I’d go to my uncle’s workshop and make things, so an interest in construction has always been there. My first degree was in outdoor and environmental education, and I worked in outdoor education for a long time. Working outdoors, you gain a connection with the natural world, which led in part to an interest in green architecture.
I ended up doing a masters in Advanced Environmental & Energy Studies at the Centre for Alternative Technology in Machynlleth in mid-Wales. The course opened my eyes to the fact that building an eco-house in the woods may be a great exemplar project, but it’s not going to solve the issues we’re facing with climate change.
At the time, I used to bang on about how we needed to bring all the things we were learning – renewable energy, water and energy efficiency, the use of sustainable materials – to the mainstream, and the best way to do that was through TV, a sort of eco-version of Changing Rooms! By chance, someone sent me an advert for a programme that sounded just like that.
It was on BBC Three and called Outrageous Wasters; I offered to be their technical consultant, but ended up working as a presenter, and it’s where I first met Joanna [Yarrow, Human Nature non-executive director], who was also on the show.
After that I ran an environmental consultancy doing thermal modelling and energy efficient design, then started a company installing renewable energy, mostly PV [photovoltaic], before going back to being a builder. When Jonathan [Smales, Human Nature Founder] and Joanna moved back to Lewes from Sweden, I got in touch – and then, a few months later, he asked if I wanted to join the team.
What’s your day-to-day role at Human Nature?
When I first started, Damian [Partington] and I shared the job of Site Manager, but I now manage the Delivery Unit. That means looking at the deliverability of the designs the architects are drawing for the Phoenix Project – as in how we will actually build them.
On a general level, I assist Chelsea [Renton, Communities and Planning Director], with all things technical about sewage, drainage and water, utilities and energy, along with Hugo [Forster, Planning and Design Coordinator], sitting in meetings and representing Human Nature. That might mean speaking to Expedition Engineering, who are working on the flood defences, Atelier Ten on energy strategy, to Southern Water or the Environmental Agency.
I’m also looking at the phasing of development of the Phoenix Project – as there are various considerations that need to be taken into account – in terms of what will be best for the people who are living in the blocks that are already finished, and what’s best from a deliverability point of view: what gives us the best construction site and the best place to store and manufacture on site components. Another part of my job is looking at things like reclaiming and reusing materials. We’re planning a resource audit of the site: how many bricks, what volume of brick, concrete blocks, how many steel roof trusses, and working out how they can be reused.
What part will timber play at the Phoenix Project?
We’re aiming to use cross-laminated timber (CLT), which is essentially like really thick plywood, but instead of veneers it’s planks of timber, which are layered and glued. That means it’s solid, really strong and you get huge spans, without the need for intermediate support, so it can be used for walls, floors, ceilings and roofs. It’s very well established in Europe, where it’s really common. There’s nowhere in the UK that makes it, so it’s not that widely used here – although a few schools have been built with it.
We’re also hoping to incorporate Sussex-grown timber as much as possible, and set up a programme where we can kind of kickstart the use of it in more mainstream construction. We would tell the local sawmills what size we would want it, but ideally we would then build the cassettes – which would have the structure, insulation and waterproof barrier – here on the Phoenix.
What about other materials such as hempcrete?
We’ve been looking at hemp fibre insulation and hempcrete, either as blocks you can buy off the shelf or as poured hempcrete. We could use that as part of the cassette system, so we’d build a big bit of formwork, which is like a big open-topped box that you lay down on its back and then fill it up with hempcrete and smooth it all off. Once it’s set, you can stand it up and it becomes a piece of wall. Hempcrete has amazing qualities – it’s really important to have thermal mass in a building. You want to have something heavy and dense, which is where concrete comes into its own, because it’s such a great substitute for natural stone, as is hempcrete.
If you imagine a church on the hottest day of the year, when you walk in it’s lovely and cool. Even though the air inside is the same temperature as the air outside as it comes in and out, the heat gets absorbed into the thermal mass of the stone. And then if you go into church in the evening, when it’s cooled down outside, the church will still be warm. What happens is the thermal mass absorbs the heat in the hottest periods and then when it cools down outside, it releases some of that heat back into the atmosphere. So, it’s a really good moderator of high temperatures.
The wall cassette system could possibly have a hempcrete layer and then an insulation layer as well – if you just do all with hempcrete the wall needs to be stupid thick in order to get the insulation values that we’d expect on the project. We’re also looking at lime renders, clay plasters, clay renders, and ways that we can use compressed chalk instead of concrete.
What are you most excited about on the site?
The Thomas Paine bridge. I really hope we get a wooden bridge – and not just any bridge, something you see and go ‘Cor, look at that!’ I’ve also been talking to the general manager of JCB recently, as they’ve just launched a fleet of electric site vehicles, small diggers and dumpers, so I’m pretty sure we’re going to insist on that here.