Located within the Dorchester's master kitchens underneath the hotel, diners can sit back and relax with a glass of champagne, while at street level the crowds rush through what is the heart of London's Mayfair.
The room is the result of a recent refurbishment of London's original chef's private dining room. It hasn't physically moved, but a very different atmosphere has been created under a partnership between the hotel chain and Champagne manufacturer Krug. Luxury and quality are the name of the game, with diners being led to the Krug Room via a sleek, stainless steel escalator to deep-red leather chairs around a specially-commissioned glass table.
But it is the clever combination of electricity and glass that will make this a truly memorable experience for diners. This synergy allows them to watch while executive chef Henry Brosi creates his masterpieces, and enjoy the activity of kitchen, while enabling a sense of privacy in the 12-seater room when desired. This has been possible by the installation of Priva-Lite intelligent glass screens manufactured by Saint-Gobain Glass. These have the ability to change from transparent to opaque by applying an electrical voltage of around 100 Vac.
Specialist glazing contractor and partitioning firm Optima Architectural Glass worked with electrical contractor Euro Property Services (London) and interior fit-out firm Vivid Interiors to install a 10 m2 Priva-Lite screen in the Krug Room to create a dividing wall between it and the main kitchen area.
The technology
Priva-Lite is essentially a laminated glass panel that comprises two panes of glass on either side of a layer of liquid crystal film. The film is sandwiched between interlayers that separate it from the glass panes, and the components are laminated together to form a complete assembly. The laminated interlayer provides an element of safety as it is difficult to penetrate.
The glass panels are electrically connected to a power transformer provided for a primary voltage of 230 V, 50 Hz via busbars along the edges of the pane. When the power is switched off the liquid crystals randomly scatter, and lie at irregular angles to each other. This gives the glass an opaque appearance, shielding anything behind it from view. Switching the electrical current on realigns the crystals so that they are all lying in the same direction, which creates transparency and enables the glass screen to be used as a conventional window.
The switching between the two states is almost instantaneous, with a standard installed pane discharge time of under 20 ms. Power consumption is low, at under 5 W/m2.
Creating the Krug Room
The Krug Room is walled on three sides; the fourth side faces the kitchen and is formed from the Priva-Lite glass. Here panels of 11·8 mm laminated glass have been installed side by side and joined by a transparent silicone seal. A mirror on the opposing wall ensures views for all.
An earthed, stainless steel frame surrounds the glass wall holding it into position and concealing the copper busbars, which run along the top and bottom edges of the laminated panels. Electrical cables at each end enable connection to a transformer with an input voltage of 230 Vac and an output of 100 Vac via an uninterruptible power supply.
A clean power supply is essential. Billy Field, Optima account manager explains: "The glass is susceptible to electrical spikes or surges. It can affect the liquid crystal and its performance." To reduce any possibility of this occurring the transformer is connected to the glass with shielded cabling to prevent outside electrical interference. Further protection is provided in this case by an online uninterrupted power supply, which is connected to the primary electrical circuit providing frequency and tension stability.
Due to this susceptibility to power quality and the fragility of the product, only trained, registered installers can complete such projects, reports Field. At present there are only three contractors licensed by the manufacturer for work in the UK, of which Optima is one.
An added complication to the Krug Room installation was that the entrance is a sliding door comprising of the Priva-Lite glass. "The door was a feat," confirms Field. Optima has extensive knowledge in sliding glass doors but this is the first time that Priva-Lite has been used in this way. The main issue was the electrical supply.
Systems that use sliding contacts, or any other method that may interrupt the current between the glass panes and the transformer, cannot be used as this will damage the glass. The supply therefore has to be made with a permanently connected cable, but allowances had to be made to prevent it from being cut or jammed while moving the door.
The solution, Field explains, was relatively simple: "We used a length of pigtail cable, which gives slack and allows movement to take place." This was inserted into a stainless steel tube attached to the top of the door pane and hidden in the channel formed by the wall's frame. "We used this tube to feed the cables into the void so they don't drag across the ceiling," he explains. A moveable, stainless steel cover attached to the back of the door ensures that the connections, or open, sliding channel, are never visible to guests.
The Priva-Lite wall and door feature are connected as a single entity to a simple, manual wall switch. A simple flick of the switch controls the mood of the room by determining whether or not the action in the kitchen is on view to diners. Remote control is another option. Again, the electrical connections must be carefully considered. The switch must be in the primary power supply loop. If it is between the transformer and the Priva-Lite, the product can be damaged.
The creation of the Krug Room was part of a £10 million refurbishment programme for the hotel. It reopened on May 19, in plenty of time for any summer celebrations.
Source
Electrical and Mechanical Contractor
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