The “Noah’s Ark” is a children’s day care centre that has an exemplary design not just in architectural and building ecology terms but also in regards to the structural technology and energy use. Two groundwater heat pumps are matched with a thermal solar power system and the heating energy is distributed with low temperatures between the rooms. A hybrid ventilation system lowers the energy requirements for heating and ventilation. The electricity required for operating the building and all other devices is generated by the photovoltaic system on the roof, whereby the aim is to achieve a positive annual energy balance. The building has been in operation since September 2013.
Additional nursery school places had to be created in the south-west of the municipal district of Höhenkirchen-Siegertsbrunn, which is situated in the Munich administrative area. The new building will also include crèche and after-school care places. Various citizens groups in the 10,000-member community pursued the idea of developing a particularly sustainable and exemplary project..
The concept for an energy-plus child day care centre enjoyed the full support of the mayor. Right at the start of the project at the beginning of 2010, the district commissioned an interdisciplinary design team comprising architects, specialist planners and a research institute for the purpose of providing scientific advice and monitoring the project. The building design convinced not just the developers but also the jury for the 2011 “Architecture with Energy” award conferred by the German Federal Ministry of Economics and Technology. The jury awarded the building a special mention with the following citation:
“A carefully harmonised building and energy concept considerably undercuts the usable energy requirements stipulated in the competition. Thanks to the use of solar thermal and photovoltaic energy, the primary energy requirement is cut to less than half of the reference building. The integral design process has ensured an excellent harmonisation between the architecture, structural design and building services technology, which enables users to engage with the building’s educational concept.”
The Fraunhofer Institute for Building Physics was involved right from the beginning in the interdisciplinary and integrally organised planning. The research institute shall now investigate how the building copes during actual use. Here the aim is to take a closer look at how the innovative components and systems interact and to record the building performance more precisely. Should the concept prove successful, the ultimate aim will be to utilise it in further comparable buildings. Not least because of this, careful commissioning of the building is particularly important. This is the task of the scientific project support, which will continue to scientifically monitor the building for the next two years following the commissioning phase.
In order to achieve the intended goal of a flexibly useable and attractive energy-plus child day care centre with a high degree of comfort, the full potential for achieving energy efficiency had to be utilised in the building design. At the same time it was also necessary to meet the special requirements placed on various child-friendly spaces. In this regard, the elongated, north-south site posed a particular challenge for the architects. The design produced has nevertheless succeeded in achieving both a southern orientation and compactness. The building, which is placed in the middle of the site, has an enlarged southern facade, which is created by a more low-lying terrace in front of it.
The chosen natural materials comprising timber (timber frame construction) and clay (specially developed clay shelving as inner walls for the group spaces) are intended to improve the indoor climate and act as a buffer for humidity and heat. Innovative system solutions are also used in order to increase the indoor comfort and the energy efficiency: PCM modules are intended to increase the thermal storage ability in the rooms, whereby acoustic baffles mounted below the wooden beam ceilings positively influence the indoor acoustics.
The energy concept is aimed primarily at minimising the energy requirement and, as a secondary objective, at meeting the remaining requirement sustainably and effectively by using renewable sources. The entire electricity requirement for the building operation and for all other use-related devices is generated on balance by the photovoltaic system on the roof. The intention is to achieve surplus electricity (a plus) in the annual balance.
To reduce the thermal energy requirements, a highly efficient building envelope is being implemented that is almost free of thermal bridges and is airtight.
The individual innovations in detail:
Hybrid ventilation system
The ventilation concept comprises needs-led hygiene ventilation that is supplemented with specific manual window ventilation. With an increased need for ventilation, so-called ventilation signals in the rooms are designed to encourage the specific use of the windows for ventilation purposes. The building is also designed for natural and passive ventilation. The passive ventilation is achieved via large, energy-optimised ventilation vents installed in the outer facade and in the foyer. A “solar chimney” installed above the foyer enhances the effect of natural, passive ventilation, which means that it is often not even necessary to activate the central ventilation system. In addition, night ventilation also enables effective passive cooling during cool, summer nights.
The central ventilation system is used during the cold and cool seasons: the supply air is pre-warmed using the groundwater. High recovery efficiency is achieved in combination with a heat recovery plant with renewable heat exchangers (heat accumulators). 90 per cent of the exhaust air heat can be resupplied to the rooms via the fresh supply air.
Intelligent control and regulation technology as well as lighting
It is intended to achieve a further reduction in the energy requirement for heating, cooling and ventilation by using intelligent control and regulation technology:
- The heating is automatically switched off in the rooms when the windows are open.
- CO2 sensors enable needs-controlled hygiene ventilation.
- Ventilation signals are used to encourage specific window ventilation.
- The side openings for the solar chimney are automatically controlled in accordance with the wind direction.
- Groundwater heat pumps and the thermal solar power system are mutually attuned with one another as heat generators and optimised in energy efficiency terms.
- Various control systems for supplying daylight and artificial lighting increase the visual indoor comfort and reduce the energy requirement for artificial lighting: controllable, light deflecting solar protection systems, daylight-dependent control systems in group spaces and offices, as well as presence detectors in sanitary spaces and basement corridors.
Low-exergy heating system
The heat is distributed at a temperature that is as low as possible so that the heat pumps can be operated as energy-efficiently as possible. It is intended that the two highly efficient groundwater heat pumps with optimised and matched components will achieve an increased annual generator performance factor (AGPF).
The operation of the child day care centre is not just about generating more energy within a year than is consumed; it is also about enabling the little users of the building and visitors to “experience” this at first hand. In addition to a child-friendly visualisation screen in the foyer (see Figures 16-19), further components have been installed in a manner that clearly shows how they work and their respective contexts. CO2 lamps are lit in the group spaces when used air needs to be ventilated away. The solar chimney on the roof can be seen from the foyer and exemplifies the natural ventilation in the building. The solar power system can be easily seen from the roof terrace and shows an important component for supplying energy to the building. In addition, further measures are being considered that are intended to foster the sensibility and understanding of the children for energy efficiency in buildings.
Further information will be made available here as the project progresses.
After just ten months a plus energy balance was achieved in the first year of operation.
|Who is who?|
|Building owner, Investor||Gemeinde Höhenkirchen-Siegertsbrunn|
|Operator, User||Evang.-Luth. Kirchengemeinde|
|Building type||Day care centre|
|Year of construction||2013|
|Gross floor are||1.858 m²|
|Heated net floor area||1.286 m²|
|Gross volume||6.436 m³|
|Work places||140 persons|
|Usable floor area AN (according to EnEV)||1.286 m²|
|A/V ratio (p.r.n. after / before Reconstruction)||0,38 m²/m³|
|Energy indices demand|
|New building / after …||before refurbishment|
|Heating energy demand (utility energy demand heat)||20,00||kWh/m²a|
|Source energy for heating and domestic hot water (dhw)||13,00||kWh/m²a|
|Overall primary energy requirement||37,40||kWh/m²a|
|Undercuts reference value||27||%|
|Building costs or renovation costs|
|Costs for the (renovation of) structural design [KG 300]||1.241||EUR/m²|
|Costs for the (renovation of) technical installations [KG 400]||640||EUR/m²|