Sustainable Building Design for Environmental Education Centre in York

The York Zero CO2 building provides a valuable community resource that serves as an Interpretation / Field Study Centre. As a focal point of Yorkshire environmental education it offers dedicated courses and facilities for local community groups, the general public and the York Education Authority including local schools and York University. The building is also a centre to promote sustainability and the implementation of Local Agenda 21, potentially combined with a one stop energy efficiency advice centre and an environmental volunteer centre for the City of York.

The building demonstrates a model of contemporary, bio-climatic environmental architecture within an urban context. It is conceived as an integrated eco system within the boundaries of the site and aims to be self-reliant in terms of its service supply systems and the treatment of its waste streams. The building is a low energy, high thermal mass, passive solar design powered by renewable energy from photovoltaics and a wind turbine. Hot water is pre heated by solar panels. The need for space heating is reduced to a minimum and is provided for by locally sourced timber, burnt in an efficient wood stove feeding a few radiators from a back boiler. Human sewage is biologically treated through dry compost toilets. Potable water is provided by collecting and purifying rain from the roof. The building forms an integral part of the disused York landfill rubbish tip. With its living green sedum roof, it is a focal point for the inner city land reclamation project to create an urban wild life park, for Friends of St Nicholas Fields, for the benefit of the whole community.


The building’s curved plan forms a 90 degree segment of a circle with its axis due north to south. The centre of the circle is formed by a wild life pond acting as an outdoor aquatic classroom for children’s dipping exercises. The N / S axis of the building alignment is marked by the Proven wind turbine position. The curved wave form cross section of the building creates a open double height central teaching space with open mezzanines to each side. The curved north roof hosts an Erisco Bauder living sedum green roof system. The south roof houses the photovoltaic electric panels and the Solus solar hot water panel system.

The building design was conceived as a hybrid, with a heavy weight super insulated masonry mass wall (with minimal window openings) to the north and a light weight heavily glazed conservatory frame structure to the south. As in David’s house the super insulated roof is formed with Fillcrete Masonite I beams spanning the main structure to form the curved profile. The I members comprise of solid 47 x 47 mm timber flanges and 8 mm hardboard webs. This makes more use of a tree than does log conversion for solid timber (using 65% less raw material than conventional timber) and can utilise forest thinnings and lower grade faster growing species to create the 300 mm depth of roof for the full fill roof insulation.

The south conservatory offers a passive solar front to the building as a pre heat buffer space and forms the entrance lobby / exhibition space providing horizontal circulation through the building and access to the vertical circulation to the mezzanines. It is normally hard to justify an isolated conservatory space in cost and energy terms. However if it is an integrated multi functional space it becomes not only a net solar gain asset for the building, but also a most beautiful sun kissed place to relax in, for very little additional cost. A particular delight in this building is the ever changing dance of refracted sunlight off the pond’ rippling surface. This beautiful quality of light dances across the conservatory back wall and ceiling, producing an effect similar to that normally seen on the surface of a yacht’s hull at sea.

Solar shading and night time cooling, from the Swedish Windows conservatory low E triple glazing, is controlled by an extensive eaves overhang and externally mounted Jalouse shutters. A well insulated and tiled concrete floor slab, with a dense concrete block back wall, provides thermal mass to the conservatory glazed space, retaining the sun’s latent heat and reducing the flywheel effect of rapid cooling down or overheating associated with most other conservatory spaces.

York Zero CO2 Environmental Education Centre Yorkshire
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Having worked hard to create a low energy design, reducing the potential energy demand for the building, we worked with Steve Wade from Wind and Sun, to design and install a novel renewable wind and solar grid connected energy supply system.

This system is designed to meet the anticipated annual electrical requirements of the building. In order to give a balanced supply throughout the year a combined wind turbine and photovoltaic (PV) solar system was used. Initially the possibility of obtaining true autonomy by means of battery energy storage was considered. However, due to the multi-user nature of building, precise electrical requirements and patterns of use were difficult to ascertain. These factors would mean any battery store would need to be large and hence unduly expensive. Since a reliable mains electricity supply was readily available (100m away) it was decided to opt for a grid connected system, resulting in more renewable generating capacity for the available budget. In this type of system no on-site energy storage is used. Power generated is first used by electrical loads in the building and any surplus exported to the grid, when power being generated is less than that being consumed, top-up is available from the grid and imported as normal. All power flows are ‘seamless’ from the point of view of the user. The aim is to achieve a numerical energy autonomy for the building with a net export to the grid over a whole year. In this situation the grid effectively acts as an ‘energy store’ instead of a site battery system, avoiding the problems of managing and disposing of toxic batteries from the site at 5 to 8 yearly intervals. Eastern Electric’s recent move to implement net metering (i.e. the same cost for import and export of energy ) makes grid connected schemes like the York building much more attractive and viable for the decentralised local production of on site renewable energy.

In order to optimise the use of on-site generation and to make energy flows transparent various displays are incorporated in the main area of the building. These show: wind turbine generation; PV array generation; building electricity consumption; and a bar graph display showing whether, and how much, power is being imported from or exported to the grid. By observing these displays, electrical loads can be managed to match available power generation and care taken so that no energy is wasted. The Eco Centre power system is made up of the following:

1.7kWp Photovoltaic Solar Array This consists of two sub arrays of 850Wp, each using 10 BP Solar 585L Saturn Cell frameless laminates wired in series to give ~ 180 VDC output. The Saturn cells used are the most efficient commercially available, and the most cost effective, giving a maximum kWh energy produced for a given roof area. The laminates are mounted on a framework above the roof, sited, in groups of five, on four sections of the conservatory roof. The framework is integrated into the roof by means of special Klober PV mounting slates, ensuring that there is no penetration of the waterproofing layer of the roof. Because of the public nature of the building, UV stabilised polycarbonate sheets are fitted above the PV’s to provide protection against vandalism. It is envisaged that these might reduce output of the PV array by approx 5%. The output of each PV sub-array feeds two SMA Sunny Boy SWR-700 inverters.

2.5kW Wind Turbine. Made by Proven Engineering this is mounted on an 11m self-supporting tower and produces power at ~ 120VDC which is fed to an ASP 2.5kW TopClass inverter. The wind turbine controller is included to divert power to a heater in the event of power outages or for maintenance. The wind turbine has good low wind characteristics whilst being protected against strong winds and should give reasonable yield despite the urban nature of the York site. The inverters convert DC power generated directly into 230 VAC. These AC outputs are then paralleled together, synchronised with the grid supply, and can either supply power to the centre’s load circuits or export power to the grid as appropriate. Each of the inverters contain protective circuitry to shut down the systems in the event of power cuts or variation of grid power quality outside statutory limits. The system  design and installation was carried out by Wind and Sun. 


The conservatory pre heat buffer zone and super insulation levels with minimal heat losses, combined with thermal mass, create considerable thermal inertia eliminating the need for a full central heating system. A 4/6kW efficient Clearview Vision wood burning stove fuelled from timbers locally harvested, provides a social focus to the main space. The 10,000 Bthu back boiler and mini max control system provides hot water to a few small radiators, which compliment the heat gains from the occupants and appliances.


All appliances have been carefully selected to eliminate unnecessary electrical demand and to optimise the efficiency of the required essential items, including low energy lighting and lap top computers etc.


All the building’s drinking and washing water requirements are met by collected rainwater from the main conservatory roof via zinc gutters, down pipes and a Wisy filter to be stored in a buried 1500 litre ex orange juice container. Water is then plumbed through a Klieber 5 micron cartridge filter and a K15S stainless steel UV steriliser to a 60 litre holding storage tank in the roof loft for gravity feed to the outlets.


One disabled and two unisex Sun- Mar Excel (non electric) dry composting toilets were fitted by Eastwood Services, with a non mechanical stack effect soil vent pipe system to allow evaporation to air of excess urine. Dried human solids, along with kitchen wastes and garden debris material, will be composted and then returned to the land as an invaluable non toxic fertiliser. The above simple system demonstrates that human wastes do not need to become toxic pollutants of our rivers and seas, but can be recycled and reused within an integrated eco-system to become an invaluable resource furthering new life within the boundaries of the site.


The naturally absorbent and breathing masonry construction creates a vapour hydroscopic envelope without the risk of condensation. Scatter rugs over timber floors, non volatile solvent, water based Ecos paints and natural OS colour stains to exposed timber along with the avoidance of formaldehyde based toxic materials, have lead to a healthy internal air quality. 


The York Zero Co2, Environmental Education Centre makes a valuable contribution to the ongoing sustainable “Building For a Future” debate. It points to a future possibility where whole community based projects could be positive energy producers rather than negative energy consumers.

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York Zero CO2 Environmental Education Centre from lake