extension and adaptation of villach town hall

urban planning and architectural aspects
the existing city hall in the district of villach – st. martin, located on tiroler straße on a corner plot opposite the park, can, under the condition of an architectural revision of its current exterior appearance, develop a radiance appropriate to the significance of a multifunctional city hall. essential aspects of the building task include:

an architectural positioning of the entire complex corresponding to a multifunctional city hall and a venue of the international central european hockey league,
the provision of attractive and weather-protected forecourts for major events,
the creation of a functional order through an appropriate foyer for the existing hall and the future training hall,
the organization of a continuous, level, and light-flooded circulation around the upper spectator tiers.

a prerequisite for the interventions is the greatest possible preservation of the existing structure. the construction of the required training hall can only take place on the southern part of the site, while various functional additions must be precisely positioned in the sense of homogenization and identity formation. the main entrance area is generously covered and located to the west. the multi-storey, clearly structured foyer between the two halls leads via the mezzanine to the upper circulation level. both halls can be visually accessed from here, thus the foyer offers additional standing areas for both halls. by elevating the circulation level, the mezzanine below can be fully utilized to provide spacious sanitary facilities for spectators. the restaurant is attractively located adjacent to the entrance and the foyer. a gallery on the mezzanine level allows a view across the skills area into the secondary ice rink. the outdoor ice bar and the adjoining beer garden complement the gastronomic offerings. the addition of the required vip area, which is also available for events and training, is positioned on the west side. the extension is precisely attached to the existing hall. boxes and multifunctional rooms are located directly adjacent to the hall. the vip stands can be reached from the multifunctional hall in a short distance. the multifunctional hall can be divided into various sizes by means of mobile elements. for the expansion of spectator seating and gastronomic offerings, the north and east sides are adapted. this also creates a clear escape route organization for the entire hall. all structural measures aim to create a continuous, light-filled circulation area with various gastronomic offers. a “new garment” on the upper floor – a continuous suspended façade made of polycarbonate panels with rotatable elements in certain areas – connects old and new, forming a clear, calm architectural frame. this new garment meets many requirements: shading, translucency or transparency when the lamellae are open, display surface, rain protection, etc. the rough charm of the existing façade may well remain as a “memory” at the ground floor level.

lighting concept
in contrast to the existing hall, the training hall is flooded with light. direct sunlight is excluded by the cantilevered roof and complete shading options. zenithal light through skylight elements is guided by light-diffusing components, thus avoiding direct sunlight. a supply air system in these roof sheds prevents condensation. the existing hall is atmospherically enhanced by the transparent circulation area.

energy concept
the aim is to develop a sustainable and energy-efficient solution for the project that considers non-continuous operation of the ice rinks and staggered commissioning (ice layer production requiring maximum cooling capacity), while viewing energy efficiency holistically as a relationship between indoor climate requirements and overall energy demand.

mechanical ventilation measures are planned in the new ice rink to ensure the required indoor conditions, adequate outdoor air supply for both the public and players, and proper air circulation within the volume. the air supplied to the stands should, if necessary, be dehumidified conventionally by cooling. the air supplied to the ice surface in the new hall is dehumidified and cooled by a sorption rotor. the cooling for dehumidification at the low temperature level is provided via a heat exchanger with a buffer storage system for low-temperature cooling, extracted from the ice rink cooling system. the sorption rotor is equipped with heat recovery to reduce the energy consumption for regeneration air.

ventilation of the new ice hall ensures that the roof, the stands, and the ice surface are supplied with fresh air, while the exhaust air is partially extracted near the floor, at the ceiling, and in the surrounding traffic and foyer areas. the training halls, event hall, and associated rooms, as well as offices, are equipped with separate ventilation systems with heating and cooling functions appropriate to their use. ancillary rooms are also equipped with dedicated ventilation systems according to their function, with particular attention to adequate ventilation of the players’ changing and drying rooms with 100% outdoor air supply. decentralized recirculating air dehumidifiers are installed in the locker rooms when needed. the ventilation of the city hall remains essentially unchanged; however, the subsequently installed dehumidification units are relocated to new technical areas and reconnected to the existing duct system.

for ice surface and dehumidification cooling, large amounts of waste heat are generated in both summer and winter. optimal utilization of this heat energy is sought to minimize operating costs, though ice production and preservation have priority over heat recovery. although the ice halls must be heated year-round, the waste heat at the condensers and desuperheaters cannot always be fully utilized, necessitating the installation of independent cooling towers.

for room cooling and ventilation system cooling at a higher temperature level, an additional refrigeration unit with a buffer storage system for low-temperature cooling is required, supplying only these building services systems. ammonia (nh3) is used as the refrigerant for these chillers as well. the waste heat from condensers and desuperheaters cannot be fully used year-round either, therefore independent cooling towers are required for these as well. partial supply to external heat consumers may be considered.

the low-temperature heat (approx. 35 °c) generated by the condensers of the refrigeration systems (ice technology and building services) is used in an energy network for heating, directly for snow pit heating (defrosting), underfloor frost protection heating of the ice surfaces (if existing, otherwise only for the new ice surface above the parking deck), preheating of domestic hot water and ice machine hot water, and air heating for the ice sports halls.

to bridge short downtimes of the cooling plant (e.g., covered ice surfaces during events) and to balance load peaks, a buffer storage system for low-temperature heat is utilized, reducing the need for purchased external heat. furthermore, a medium-temperature heat pump, supplied from the low-temperature network, together with the desuperheaters of the refrigeration systems, feeds the medium-temperature heating network (approx. 50 °c), which is used for reheating domestic and ice machine hot water, space heating, and general air heating.

to supplement heating capacity during periods of low waste heat generation (e.g., covered ice surfaces during events) and to bridge shutdowns (e.g., melted ice surfaces in summer), the existing district heating connection with transfer station is retained, supplying a buffer storage system for medium-temperature heat. it is assumed that the existing district heating capacity is sufficient and does not need to be increased. additionally, a high-temperature heat pump is supplied from the medium-temperature network, feeding the high-temperature network (approx. 100 °c), used for the hygienically necessary heating of domestic hot water (via decentralized hot water loading stations to minimize heat exchanger water content) and for heating the regeneration air of the sorption rotor.

space heating is provided throughout by air heating, surface heating, and radiant ceiling panels. the existing heating systems in the city hall are integrated into the new energy network according to their temperature level. space cooling is provided throughout by air cooling, surface cooling systems, and, if required, additional recirculating air-conditioning units.

to reduce water consumption during ice maintenance, the already treated meltwater from the snow pit is filtered, stored in a cistern, and reused for ice machine hot water preparation. generally, self-closing fittings are planned to reduce water consumption, and the required flushing to prevent stagnation at shower fittings is centrally controlled.

the cooling system for the existing and new ice surfaces is designed as a common indirect system using a brine coolant (glycol-water mixture) within the pipe system of the ice layer. a new refrigeration plant using natural refrigerant ammonia (nh3) will be installed in a machine room for brine cooling. the combination of cooling systems for both halls allows an overall reduction in system size. to ensure high operational reliability, refrigerant and brine pumps are provided with 100% redundancy; four identical compressors are installed, each capable of maintaining the ice quality in one hall. ice formation in one hall and simultaneous ice quality maintenance in the other hall are ensured by three compressors.

to cover load peaks and utilize solar power from the pv system, an ice storage unit is integrated into the rink’s cooling system. for heat rejection, a connection to the existing well system (groundwater cooling) is planned to the extent possible, equipped with a heat exchanger. additionally, cooling towers are required as necessary, with the existing unit being relocated and reused.

for partial supply of electrical consumers, a large-scale grid-connected photovoltaic system is planned. the pv system consists of modular photovoltaic panels installed on the roof surfaces. the direct current generated by the pv modules is converted via inverters and fed into the local power grid through a feed-in meter, with priority given to self-consumption of the generated solar electricity. the remaining power demand is supplied via the utility’s metered connection.