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Novum Hotel Bruy, Stuttgart Heating and cooling take pole position

2 | Uponor – Novum Hotel Bruy, Stuttgart

Successful modernisation of the Novum Hotel Bruy Contec ON – near-surface thermal active building system with single-room control in the extension building Klett underfloor heating and Renovis ceiling cooling guarantee comfortable temperatures even in the attic rooms Smart ISI box simplifies washbasin installation The brand Porsche and the Zuffenhausen district of Stuttgart are inextricably linked. And this link can be experienced at the Novum Hotel Bruy. The business hotel in the north of Stuttgart, which has been extended and converted multiple times and which is newly renovated, is where Hans Hermann and Richard Attwood celebrated into the early hours on the occasion of Porsche’s first overall victory at Le Mans in 1970. Posters, pictures and memorabilia hark back to the 1970s and 80s, which were a wild time in motorsport too.

Porsche is now focusing its motorsport activities on Formula E, while Bodo Bruy is putting the hotel with 128 rooms into pole position in terms of its heating, cooling and ventilation with a scientifically developed energy concept. Uponor advised the hotel owner, assisted him with project planning and supplied a total of approximately 1,200 m² of Klett underfloor heating, 2,000 m² of Contec ON – near-surface thermal active building system and 600 m² of Renovis ceiling heating and cooling for the modernisation.

Roaring past: its where Hans Hermann and Richard Attwood celebrated Porsche’s first victory at Le Mans in 1970.

Porsche´s just around the corner The Novum Hotel Bruy is just a few minutes’ walk from Stuttgart’s Porsche Museum, which has now been attracting automobile aficionados and lovers of architecture from all over the world to the city for more than ten years. Nonetheless, Bodo Bruy realised early on that the special history of the hotel, which started out as a simple restaurant, and its proximity to Porsche were not strong enough as USPs for the business to continue to generate an adequate return in the long term in the highly competitive Stuttgart hotel sector.

Over the years, the hotel has grown to its current size of 128 rooms thanks to extensions, conversions and the purchase of an adjacent building. The building wings which have evolved along two streets are connected by a central building and the breakfast rooms on the ground floor.

As a qualified electrical engineer, it was clear to Bruy when he took on his parents’ business in 1993 that, considering the complex structural situation, the only way to reduce the energy costs while boosting the hotel guests’ comfort was with a very good overall building services concept. Energy currently accounts for around 5% to 7% of a hotel’s costs – and this percentage continues to increase.

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Bodo Bruy didn’t simply make do with installing LEDs and reducing overnight heating and hot water generation. By 2008, he had already installed the first combined heat and power system.

A coherent energy concept that works and - looks good Bodo Bruy developed a convincing energy concept for the hotel’s modernisation together with Prof. Dipl.-Ing. Georg Sahner, G.A.S. Sahner, Stuttgart. It is founded on a gas-powered peak load boiler with output of 210 kW and a gas-powered combined heat and power system with electrical output which can be modulated in the range of 5 kW to 20 kW and thermal output in the range of 10 kW to 43 kW. This generates all the heat and 90% of the electricity needed. The CHP system was run for between 4,000 and 6,000 hours a year in recent years, depending on the hotel’s capacity utilisation and the weather conditions.

Running a CHP system reduces heat and electricity generation by up to 41 t of CO2 per annum in comparison to conventional generation.

The heat generation system is complemented by a solar thermal system measuring 88.56 m² with installed capacity of 61.99 kW. Annually, 56.16 MWh of energy are fed into the drinking water network via five freshwater modules, each with output capacity of 80 l/h at 60°C. A daily drinking water requirement of 3.75 m³ was assumed. A further 70.48 MWh of solar energy are available for heating and 107.3 MWh for the auxiliary heating. Three 3,000 l buffer tanks provide storage. Thanks to the near-surface thermal active building system (Contec ON), the supply temperature of the six heating circuits is limited to the range of 26°C to 35°C depending on the outdoor temperature – ideal for making use of the stored heat.

The solar thermal system saves 5,317.7 m³ of natural gas and 11.25 t of carbon emissions a year. A further energy and carbon reduction could be achieved with the planned installation of an adsorption chiller, which will be used for solar thermal back-up in cooling mode.

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Before the first work began in 2015, G.A.S. Sahner calculated the heating and cooling loads of every room under realistic conditions that also took into account the internal loads caused by guests and the use of electrical consumers. The result: The building (~ 2000 sqm) has an average cooling load of 411 kW. Affected by the location of the building high solar gains are collected. This in particular affects the hotel rooms in the attic (~ 600 sqm). ‘We designed everything on the basis of the cooling load,’ emphasises Michael Rebel, Technical Consultant at Uponor. He was responsible for overseeing the project on-site, advising the building owner and coordinating the Uponor project planning team’s calculations for the radiant heating/-cooling systems.

The building (~ 2000 sqm) has an average cooling load of 411 kW. We designed everything on the basis of the cooling load.

Michael Rebel, Technical Consultant at Uponor

The external walls of the new part of the building were built using heat-insulating bricks, this also reduces the cooling load in summer. In the case of existing building components, a thermal insulation composite system was used. The windows are fitted with triple glazing. In order to reduce the solar radiation into the rooms, electrical roller shutters are used. Depending on the rooms’ location, intensity of sunlight and time of year, they care for shading automatically.

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The idea: noiseless, hygienic, draught-free and energy-efficient To determine the hotel rooms’ heating and cooling loads, it was assumed that there was an average supply air flow of 50 m³/h from the ventilation system and a room temperature of 25°C in cooling mode and 22°C in heating mode. But rather than heat and cooling being distributed by fan coil units, which are still common in hotel rooms, Bodo Bruy wanted noiseless, hygienic, draught-free and above all energy-efficient heating and cooling in his highly individual rooms.

Based on the structural circumstances, he opted for a custom overall heating and cooling solution from Uponor. This also meant the ventilation system could be given a smaller dimension. Ventilation is provided by two central ventilation machines with capacity of 4,000 m³/h.

The ventilation system’s efficiency is boosted by auxiliary modules for pre-cooling and -heating as well as for heat recovery.

Three floors added to the rear of the building are heated and cooled by Uponor’s Contec ON – near-surface thermal active building system. Guests can individually adjust the temperature of their room to suit thanks to single-room control. The Uponor Comfort Pipe Plus pipes running through the honeycomb grid of the Contec ON system lie just a few millimetres beneath the surface of the concrete soffit. As a result, unlike conventional concrete core activation, the system is able to respond instantaneously to changes in the desired temperature. ‘The guests can regulate the preset temperature by three degrees up or down on the display. It’s easy for everyone to understand and it simplifies operation,’ explains Bodo Bruy.

The rooms in the existing parts of the building are heated with Uponor Klett underfloor heating, which is very easy to install. The pipes are delivered ex works with hook-and-loop tape spiralling around them and are simply pressed onto the laminated insulation board at the calculated intervals. This means the pipes can be swiftly and economically installed as a one-man job and also subsequently corrected without the need for special laying and fixing tools. This flexibility allows the laying of the pipes to be adapted to any room geometry. With the rooms at Hotel Bruy having a variety of layouts, this saved a great deal of time.

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In addition to underfloor heating, the rooms in the existing building were equipped with Uponor’s Renovis ceiling heating and cooling, which is operated by means of single-room control. In cooling mode, the chilled water which is up to 4°C cold is available. Depending on the external temperature, this is brought up to a supply temperature of between 18°C and 23°C by means of admixture and is fed into the six cooling circuits via a simple Tichelmann manifold.

The Uponor Renovis dry construction element consists of 15 mm thick plasterboard with the PE-Xa pipe already integrated. The elements measuring 200 × 62.5 cm, 120 × 62.5 cm and 80 × 62.5 cm can be installed onto existing walls and ceilings like a dry construction board by means of a substructure made of commercially available 27/60 CD profiles.

Following the simple attachment of the Renovis elements to the heating and cooling pipes, the open ceiling or wall sections are sealed with commercially available dry construction boards. The joints are then filled and smoothed down, and the Renovis elements then serve as the new wall or ceiling. The printed laying of the pipes makes installing recessed lights, air outlets or sprinklers safe.

I was looking for systems that could do both heat and cool.

The Renovis and Contec ON systems can do just that.

Bodo Bruy, Building owner, Building technology planner

Clever installation solutions for the hotel bathrooms As the project manager, Bodo Bruy appreciates simple installation solutions.

He was therefore also impressed with the Uponor Smart ISI box. The prefabricated installation unit is fully encased in closed-cell PUR foam and is ideal for installation in drywalls – a construction method typically used for internal bathrooms in hotels.

All the necessary drinking water components are preassembled in the Smart ISI box ready for connection. The ISI box therefore allows for especially swift and safe installation. The high-quality insulator offers top heat insulation up to the drinking water withdrawal point as well as sound insulation which exceeds the requirements of DIN 4109 and meets those of VDI 4100:2012-10.

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130 Smart ISI boxes were installed at Hotel Bruy, with the withdrawal points for two rooms at a time being brought together to create a loop installation by an Uponor Uni Pipe PLUS composite pipe. In contrast to conventional tee connector or serial installations, in this case, the individual withdrawal points are supplied with water in a loop from two sides, rather than consecutively. They are therefore always fed from two directions, meaning the water in the pipes is completely replaced every time water is drawn off. By this stagnation of water can be essentially eliminated in the case of normal usage. At the same time, this means small and uniform pipe diameters can be used, which both minimises the water content and allows for straightforward installation.

Building and room management The entire system, from generation, buffering and recovery up to the individual consumers, is monitored and managed by two coupled bus systems. The generators with buffer storage and the provision of fresh water and cooling water are monitored and managed by a CAN bus system. The individual rooms’ air conditioning, shading and lighting are controlled by the KNX-EIB system.

In addition, the ventilation system and electricity meter consumption and feed-in data is collected. All the data is then fed into a program for visualisation purposes, thereby providing information about the status of the system as a whole at all times. This means malfunctions which may arise can be identified swiftly and reported to Facility Management. It also means future climate figures can be incorporated into the building parameter calculations.

Project participants

Products

• Building owner: Bodo Bruy • Project management and energy concept development: Prof. Dipl.-Ing. Georg Sahner, G.A.S. Sahner, Stuttgart • Building technology planning: B-iT KG, Dipl.-Ing. Bodo Bruy, Stuttgart • Building technology execution: Berner Elektrotechnik, Heizung und Sanitär, Stuttgart • Project planning for heating, cooling and drinking water supply: Uponor GmbH • Supplier of heating, cooling and drinking water supply: Uponor GmbH

• Underfloor heating: 1,200 m² of Uponor Klett 25-2 underfloor heating roll panels and Uponor Klett Comfort Pipe, 16 × 1.8 mm • Ceiling heating and cooling: 600 m² of Uponor Renovis • Near-surface thermal active building activation: 2,000 m² of Uponor Contec ON with Uponor Comfort Pipe Plus, 14 and 20 mm • Washbasin and shower water installation: Uponor MLC ISI box • Heating/cooling manifold: Uponor Vario S stainless steel manifold • Drinking water supply: 3,800 m of Uponor Uni Pipe PLUS composite pipe

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Moving Forward Uponor is a leading international provider of solutions that move water for buildings and infrastructure. We’re rethinking water for future generations with our safe drinking water delivery systems, energy-efficient radiant heating and cooling systems, and reliable infrastructure solutions. With a commitment to sustainability and a passion for innovation, we’re developing new technologies and systems that build confidence and enrich people’s lives.

That’s moving forward.

And that’s what Uponor is all about. www.uponor.com

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