Straw Bale Solar Powered Showers
The straw bale shower block at The Sustainability Centre is located on the campsite, for people staying in our yurts, tipis or tents. It has two shower cubicles and one fully accessible wet room. There are also washing-up sinks and a hand basin.
Straw bale construction is a method of building that uses straw as a structural building material, or as insulation, or both. In this case, the structure is non-load bearing with a timber frame. Straw has several advantages: it is cheap, readily available, renewable and highly insulating.
We sourced the wheat straw bales for this building from the farm next door. The straw has been lime rendered for weather-proofing. Lime is a traditional, natural building material and has a much lower embodied energy than modern cement renders.
The timber frame of the building is made from low-grade softwoods sourced within five miles of The Sustainability Centre. The roof is made from locally sourced cleft chestnut shingles. The shingles were made on site by a local coppice worker and his apprentices.
The foundations of the building are designed to have a light touch on the earth. The building rests on piles made from recycled tyres filled with rammed chalk from the site. This means that the 'footprint' of the building is minimal.
The water soaks away into a French drain filled with recycled tyre chippings. Finding creative uses for old tyres is important as they pose a significant waste problem. They are designed to be hard wearing, weather proof and don't degrade easily. They can also be hazardous if they catch fire; a fire in Wales in a dump of 10 million tyres burned for a staggering nine years and produced vast quantities of harmful emissions.
Evacuated glass tubes filled with a non-toxic liquid provide the heat for the showers. When sunlight hits the panel, the liquid inside turns to gas and rises to the top of the tube. The heat from the gas is then transferred to a pipe of glycol that is in a closed loop, which then goes on to the boiler to heat the water.
A small electric motor is used to pump the glycol around the system, and the water temperature is monitored and regulated by a control box . The whole installation when fully operating will provide enough hot water for up to 30 showers per day. To allow for constant use all year round we have added an immersion heater back up; after all, we are in the UK!
The flooring of the showers is cork, which may seem like a throwback to the seventies but is actually a very good sustainable product. Cork can be harvested from the same tree for about two hundred years and every harvested cork tree fixates between 3 to 5 times more carbon. The harvesting is made with minimal impact on the environment and no trees are cut down.
The Belfast sinks and teak draining boards have been reclaimed from our derelict accommodation building.
The original plan for the showers was to harvest rainwater from the hostel roof, but this eventually proved to be outside of our budget. We plan to install the rainwater harvesting element of the shower block at a later date.