Project: Multifamily Residence Frauenfeld
Architecture: Ivanov & Partner
Project Management: Dimo Ivanov
Builder: homebay
Structural Engineer: D+S Baustatik
Building Physics: soundtherm
Lighting Design: S&S elektrodesign
Location: Frauenfeld, Thurgau, Switzerland
Area: 1424 m2
Year: 2022
Photo Credits: Foter.sk / Matus Nedecky
The new building on General-Weber-Strasse in Frauenfeld is not an ordinary multi-family residence, but a symbiosis of a classic apartment building with 6 condominiums and a luxury penthouse, which extends over the entire attic floor (approx. 400 m2) and over the roof garden (approx. 150 m2). The owners use three of the 7 units for their own needs: penthouse / attic, a 4.5-room apartment on the first floor, and a 2.5-room apartment / office on the ground floor. For this reason, the three units are directly accessible via a private elevator access. In this way, a part of the residential building is used similar to a single family house by the same family.
In terms of urban planning, the building is very compact and modest, but at the same time opens up to the outside through large-scale floor-to-ceiling windows and thus communicates in an urban way with the immediate urban surroundings. Terraces and loggias are provided on all sides of the Multifamily Residence Frauenfeld, so that architecturally all four facades are treated equally.
The large attic terrace faces northwest and offers a wide panoramic view of the city. The slope and the orientation of the plot guarantee an unobstructed view in the long term. On the street side, a smaller covered loggia is provided, which is connected to the large attic terrace, creating a total terrace area 135m2 and 270°.
The centrepiece of the penthouse is the patio located in the middle of the attic floor. The approx. 40m2 patio is completely glazed on three sides, the remaining facade surface is clad with large-scale porcelain stoneware tiles. Two perforated windows penetrate the opaque patio façade and extend the view from the rooms behind. Behind the window in the kitchen, for example, there is a lounge area with seating so that one can enjoy the view of the patio. Apart from ventilation and lighting, the patio fulfills an additional function as a passageway and connects the attic floor with the roof garden via a metal spiral staircase (see chapter Spiral Stair).
Facade design
One of the highlights of the Multifamily Residence Frauenfeld project is the ventilated metal facade made of anodized aluminum. The appearance of the facade is dominated by the horizontal aluminum profiles, which were attached to the outer metal layer (base sheet) by means of a clip mechanism. The aluminum profiles are anodized, which does not produce a homogeneous color, but a changing color gradient depending on the light conditions / position of the sun. When anodizing aluminum (also called anodizing), the top layer of an aluminum component is transformed into a robust oxide layer by anodic oxidation. Anodized aluminum components are protected against wear and corrosion, exhibit improved sliding behavior and have a noble appearance.
The second layer behind the aluminum profiles consists of dark-coated base sheet. The black coating visually reinforces the structural depth of the facade. For reasons of building physics, the facade system was developed with a special substructure that enables connections without thermal bridges. An important aspect of the architectural design was the precision of the facade, which allowed neither visible roof edge covers nor window sills or other technical superstructures and fixtures such as spouts, emergency overflows, pipes, parapet covers. Whether roof edge, window sill or large homogeneous surface, the appearance of the facade remains always the same.
For windows where privacy is important, such as bathrooms or windows with formats that do not fit into the facade grid, the base sheet was perforated, but the aluminium profiles are continued (see illustration: detail perforation). This allows a lot of natural light to pass through, but privacy protection remains. The wide colour spectrum of the building facade comes into its own in changing light conditions. This is clearly visible in the colour difference in the ‘Detailed view’ and ‘Corner detail’ images.
Penthouse
The culmination of the Multifamily Residence Frauenfeld is the penthouse, which includes the entire attic floor and the roof garden. The penthouse consists of approx. 230.0m2 net living area, approx. 170.0m2 terrace area incl. patio on the attic floor and approx. 150.0m2 roof garden area incl. pool. The attic apartment is already accessed one floor below, i.e. on the upper floor, and the staircase between the upper floor and the attic floor is located entirely within the attic apartment (see illustration).
The apartment’s internal elevator, accessible only to the penthouse residents, stands freely in the room and was clad in wood. Visually, the lift integrates as an extension of the built-in furniture. The open floor plan divides into different areas depending on the room function and privacy. The 70m2 living space is surrounded by terraces on four sides and opens to all directions. Regardless of the position of the sun, there will always be terrace area that is in the shade and those that are sunny.
In order to achieve even more comfort and safety while at the same time reducing energy consumption, the building owners opted for a fully comprehensive ‘KNX’ building automation system. This intelligent bus system of the electrical installation is used to enable networking of all components of the house and building system technology. Functions such as lighting, shading, blinds control, heating and ventilation, multimedia and household appliances, but also the photovoltaic system including battery storage, an energy monitoring system and the charging station for the electric cars are networked uniformly, intelligently and efficiently.
Frameless sliding glass doors and windows
In many design decisions, the architect came up against the absolute limits of technology. For example, for the frameless sliding windows, the largest possible elements were ordered from the contractor swissFineLine. The size of the individual elements is up to 6.0m x 3.0m, resulting in a total glass area of max.18m2 per element. In addition, the individual elements are motorized and networked with the building automation.
Since a large part of the attic apartment is completely glazed, the summer thermal insulation was crucial for the compliant indoor climate. It was very important to the building owners that a pleasant temperature of approx. 23 °C is achieved without air conditioning even in midsummer. In order to fulfill this demanding task, various planning aspects were taken into account: architectural, building physics, as well as building technology. The architectural response was the recessed glazing of the living space. The apartment with its 8 facades (incl. patio), which can be completely or partially opened, can be completely ventilated, which also contributes a lot to the summer heat protection.
Another innovative system that has been implemented is the so-called TABS. TABS are an energy-efficient, innovative system solution for heating and cooling buildings of all kinds. In this process, the building mass, namely the concrete, is used as an energy storage and radiation surface. In TABS systems, the building mass is used as a thermal energy store and supplied with low operating temperatures. This has a positive effect on the performance efficiency of heat pumps and reduces the energy costs incurred. Geothermal energy sources (ground probes) were used for bivalent operation (heating and cooling). The system provides a lot of comfort in the rooms throughout the year, because the energy exchange is mostly through two thermally activated surfaces (floor and ceiling).
Pool design
The clients originally wanted a pool in the garden on the ground floor level, but still only accessible privately. After a detailed study of variants, in which all pros and cons were weighed up, the decision was clearly made to integrate the pool in the roof as an element of the penthouse. Pro-arguments: Exclusivity because on the roof. 360° panoramic view. Privacy. Enormous enhancement / highlight of the roof garden.
Contra-arguments: approx. three times the budget. Enormous planning effort.
Due to its very high complexity, the pool planning has developed into its own separate project, whereby different variants, materials and technical designs were examined. In addition to the structural design, the greatest challenges were the building physics requirements, the technical installations, the architectural design of the transitions and the fulfilment of all safety standards with regard to fall protection.
The pool (net basin size: approx. 11.0m length, approx. 3.0m width, approx. 1.5m depth) is placed in the roof garden between the patio and the attic terrace. In order to achieve the necessary depth in the pool area, the two rooms below the pool (kitchen and 2nd guest room) are only 2.40m high (= standard height), the remaining rooms are just under 3.00m high. Access to the pool is via the patio, vertical access is via a spiral staircase in the middle of the patio (see next chapter). The pool facility is fully integrated into the architecture, whereby the pool use cannot be guessed from the outside. This protects the privacy.
From a building physics point of view, the system would have to be completely decoupled from the building; the pool must not have any points of contact with the shell of the building. To meet these requirements, a special insulation ‘ISOLMER® -16 – HBT-ISOL’ was used.
In a modern pool installation of this type, the innovative pool technology is crucial for functionality as well as for water quality and general well-being. The pool technology is located in a separate pool technology cabinet on the other side of the roof garden. The pool technology consists of: Filter system with automatic filter cleaning, smartphone control, measuring and control technology for automatic water treatment, swimming pool cover, counter- swimming system, automatic pool cleaning, etc.
Spiral stair
The spiral staircase placed in the center of the patio does much more than just connect two levels. Architecturally, this staircase was intended to be a large-scale sculpture that was put on display in the patio and could be viewed from anywhere.
In order to achieve this sculptural character, the architect designed a seamless construction ‘as if from one cast’. There was to be no support in the middle of the staircase; the soffit and side elevations are smooth and seamless so that the homogeneity of the volume is maintained. The realisation of the design was technically very demanding: the railing in the stair eye was made from a tube by laser, the soffit was only mounted and welded afterwards. The stair was completely produced and coated in the metal workshop. The whole staircase structure was delivered to the construction site, lifted to the site by means of a pneumatic crane and anchored.
Underground garage Multifamily Residence Frauenfeld
The underground garage of an apartment building is usually architecturally neglected and often dominated by technical installations. The goal in this project, however, was to make the underground garage feel like an extension of the living space. To achieve this, the surfaces were treated accordingly: The floor was coated with synthetic resin, and the walls were painted with a special metallic paint.
The interior design of the underground garage is characterised above all by a high-quality lighting concept. Accordingly, round designer lamps have been combined with built-in LED strips.
