‘The Village’ is an ambitious and highly innovative Eco Village in Cloughjordan, County Tipperary, which was recently voted the greenest community in Ireland. The site covers 67 acres (27 Hectares) and will eventually include 114 homes and 16 live-work units. So far, around 40 houses and a visitor hostel are occupied, all completed as individual build projects by the site purchasers. About 40 more plots have already been sold and building on some of these will start during 2012. The early years of rapid growth have been halted by the collapse of the ‘Celtic Tiger’ economy and the end of the housing boom in Ireland. However, site sales and new building starts are continuing – and there are none of the houses abandoned half-built that are so common elsewhere in Ireland.
A wood fuelled district heating system was planned from the start and this was later modified to include heat from a 500 square metre array of solar thermal panels, the largest in Ireland. When the sun shines over Tipperary, and it often does, the solar array supplements heat from the two 500KW boilers fuelled by woodchips. A day without sun is rare, even in Ireland, and in the summer a couple of hours of sun will meet all the expected heat demand for the complete development, avoiding the need for the duty boiler to fire up. And even in mid-winter, one duty boiler will meet the full demand, allowing the second to act as back-up, which facilitates maintenance. Duncan Martin, who has been involved in the development since 2002, explained how the system works. Click here to see a short video.
The district heating system has worked very well since it was fired up in October 2009 but has not been without problems. Delays in completing the development were not planned for, so hot water is currently pumped round the whole site even though only 40 homes are connected. So heat losses and some overheads are the same now as they will be when the ecovillage is complete. This is obviously less efficient.
The DH system is managed and operated by a not-for-profit management company, of which all site owners are members. It sells heat to residents at cost, based on metered usage. The heat charge in May 2012 was 3.5c/ kWh, when kerosene fuel for oil-fired boilers was around 10c/ kWh. The fixed costs, including the cost of heat losses, are covered by a standing charge of €23.09/ month applying to all sites. This means that people who have not yet started building, and may be unable, for various reasons, to do so, are still paying towards the costs of the district heating system. Naturally some feel this to be unfair – but the community felt that it would be even less fair to expect members who built first to carry the whole of the fixed cost.
There are still a few technical problems with the solar thermal array. Perhaps this is not surprising in a system which is the largest of its kind in Ireland.
As Duncan explains in the video, the designers made no allowance for the occasional period of prolonged hot weather when the system could produce more heat than needed nor for the phasing needed until the ecovillage was complete. This is a major design flaw because overheating can cause gradual breakdown of the glycol fluid which then begins to corrode the solar panel. It may be necessary to reverse the pumping system at night so that heat can be dumpedon the rare occasions when Ireland gets a heatwave.
Inadequate air venting has also been a significant problem: glycol-water mixtures tend to form micro-bubbles, which do not escape through the simple vents used in hydronic systems. Luckily, both problems can be rectified quite easily, although liability for the cost remains a matter for negotiation.
Despite these difficulties the system meets the heating and hot water needs of 40 homes and is expected to cope easily with over 130 buildings when the site is completed. But not all residents are convinced. John Joplin, one of the early house builders, said: “I’m still waiting to see if the district heating system turns out to be better than having my own wood stove and back boiler.”
Looking at the small amount of smoke coming from the chimney of the district heating system – scarcely more than you would expect from a single woodburner – it’s easy to believe that collective systems are more efficient. Denser developments would certainly not have space for every home to have their own woodpile.