Triangle of sustainability
In Hørsholm, north of Copenhagen, what may well be Denmark’s most environmentally friendly kindergarten has opened its doors. The triangular construction from the architects Christensen & Co. doesn’t just generate more energy than it needs, it also offers children optimal conditions with plenty of sunlight throughout.
The task that Hørsholm’s local authorities put to participants in an investor’s contest for the new kindergarten was a challenging one: construct an energy-plus-building for the same price as a ‘normal’ kindergarten. In addition, it should be an ‘active house’ with plenty of daylight, a comfortable indoor temperature and a high quality of air to provide the best possible conditions for the circa 100 children and 30 adults who would work and play there. The project was named ‘Solhuset’ – ‘sun house’.
Five teams, made up of construction companies, architects and engineers, took part in the contest. The winning entry came from Hellerup Byg, Rambøll and Christensen & Co. from Copenhagen. Their entry, which changed only slightly from the contest to realisation, envisaged a compact building with a triangular shape that followed the form of the plot of land. The north of the 1,300m2 building is home to administration rooms as well as the bedrooms, which remain unheated even in winter. This is typical of Danish Kindergartens: outside air comes in through gaps in a board partition, which slightly resembles a solarium in sanatorium. The group rooms and the eating area are arranged along the south-eastern and south-western facades, while the centre of the building contains the more open areas and interactive space, which are lit solely from above. Two greenhouses are located on the corners of the building – they are a key part of the educational concept, which aims to teach children the importance of respecting the environment and maintaining a healthy diet from a young age.
The guiding idea behind the design was to build a ‘mini town’. Instead of a flat roof, the kindergarten has four pitched roofs, one behind the other running from west to east. This can also be seen from inside, meaning that no two rooms have the same layout and profile. The interior materials are simple, light in colour and reflect the ‘sunny’ name of the building. Both walls and ceilings are all white, while the flooring is made of sun flower yellow linoleum. In contrast, the facade is covered with near-black ‘superwood’, which is made under a high heat and pressure without the use of conventional timber preservatives.
Daylight simulations resulted in an average daylight ratio of 7% in the rooms along the facade – three times what the relevant Danish norm requires. Rooms further inside the building are provided with plenty of sunlight via skylights and roof lights in the piding walls. Here, the daylight ratio can be up to 4%. In times when daylight isn’t enough, automatic LED lighting can be activated.
The windows are an active part of the hybrid ventilation concept: the building does have a ventilation system installed with heat recovery, but this is only used in winter. As soon as the outside temperatures reach a certain level, automatic window ventilation kicks in, which ensures the rooms have sufficient air and that the temperatures and CO2 levels are at acceptable levels.
Grey energy is also redeemed
Both the design and the systems engineering ensure that the building reaches the energy-plus standard: the building envelope – made from prefabricated wood – is well insulated; the massive interior walls and the flooring provide thermal storage for the large amount sunlight that comes in from the skylights and windows. According to calculations, these cover half the heating requirements in winter. The other half – around 29 kWh/m²a – are supplied by solar panels as well as a geothermal heat pump, which is connected to a 1,000m long underground collector. With a primary energy requirement of 51 kWh/m²a, the kindergarten meets the Danish energy class 1, meaning it already fulfils the planned requirements for the Danish building codes in 2015. During the course of a year, it is expected that the photovoltaic system will produce 9kWh more solar energy than the building and all its appliances will need in the same period. This excess energy will be fed into the public supply. Theoretically, it should be enough to balance out the ‘grey energy’ used to construct the kindergarten within 40 years.
To see whether the ambitious goals can be realised, energy consumption and generation will be constantly monitored. Already in the building’s first two months since coming into service (March and April 2011), the photovoltaic system has generated three times more energy than the kindergarten has needed in the same timeframe. In addition, every room contains sensors that monitor the inside temperature and the CO2 content in the air. In order to recognise and solve problems as quickly as possible, construction engineers and kindergarten staff meet every month. Solhuset will also be the focus of no less than four different study projects in the coming months. Amongst other things, they will be investigating indoor environment quality and incidence rates, comparing the new kindergarten with its two predecessors to evaluate whether the ‘green’ educational programme has any affect on the behaviour of either children or their parents.