Devonshire House
74,000 sq ft
Devonshire House Offices - Building Expertise - Moving Offices - 1

Devonshire House

The recently refurbished 4th floor of Devonshire House has been designed and constructed to a very high standard. The building is located on an island site bounded by Piccadilly, Stratton Street, Mayfair Place and Berkeley Street in the heart of Mayfair.

Maris Expertise
Maris has completed an office design & fit-out project for Highbridge Capital Management at Devonshire House. Great natural daylight and user driven space planning, drive the design for the desking at the new office. Flexibility was kept in mind when designing this space.

Traditional foundations appropriate to a property of nearly 90 years of age. The property was rebuilt in 1924 and its substructure and construction can be described as substantial.

The superstructure comprises of concrete floor slabs and a steel frame.

Floor Loading
• Offices 2.5KN/m2 (+1KN for partitioning)
• Basement and plant enclosures up to 7.5 KN/m2

Wood sash windows with anodised secondary double glazing into Portland Stone façade. Lightweight glazing curtain walling to Atrium / lightwell.

The roof construction is traditional concrete structure. A structural engineer will need to assess any additional proposed roof equipment.

• Planning module 3.7m approximately
• Column grid 3.7m – 4m centres
• Raised floor zone 100mm to top tile
• Floor to ceiling 2,500mm / 2,350mm
• Slab to slab height up to 3,150mm

Noise Rating
Landlords provide clarification that their property has been designed to operate, whilst producing low levels of noise emission. This property is confirmed to comply with the following noise ratings:
• Offices (open plan) NR38
• WC areas NR45
• Reception NR40

These ratings are industry recognised standards and provide a low level of noise emission from the base build services.

Entrance Hall
The reception entrance hall is enclosed by double height feature walls and is accessed from Mayfair Place

The floor is finished in stone, setting the standard for the quality of installation. Ornate historic and modern features and provide a crisp appearance to the area with integral feature lighting.
At present, security is provided at the property’s bespoke feature reception desk. Clarification should be sought from the Landlord regarding security provision and receptionist duties / working hours.

A refuse and recycling bay is provided with direct access to Stratton Street and internal access from Core 2 no. service lift.

WC / Bathroom Facilities
WC bathroom facilities are located in each core, some of which could be shared by adjoining tenants. In addition core 2 can also be accessed from the lift lobby. All WCs are Unisex with wash hand basins within each cubicle and disabled WC facilities are positioned in core 2 and 3. The WCs are finished to a high quality with ceramic tile finish to the floors and quality fitments.

3 no. male and 3 no. female showers are provided on the lower ground floor, incorporating lockers and changing facilities for those members of staff who either choose to cycle into work or those running and / or using local gym facilities throughout the day.

Cleaner’s Facility
A Cleaner’s facility has been installed within the Landlord’s common areas within core 3. The single cupboard incorporates a Cleaner’s sink with drainage top and sufficient space for the storage of cleaning products.

Cycle Provisions
Within the car park area a designated cycle store area is provided at lower ground floor level, accessible by lift and adjacent to the shower and locker facilities.

Raised Floors
Medium grade, full accessible raised floors are provided throughout the floor. Floor tiles are 600mm x 600mm wrapped galvanised steel on adjustable pedestals. Floor voids are 70mm allowing passage for your IT / telephony cabling and an underfloor power distribution system.

The ceilings are covered by a fully demountable suspended ceiling with a slim-line grid and 750mm x 750mm perforated metal ceiling tiles. The ceiling void is approximately 550mm at its deepest point (excluding dropped beam locations).

All walls and columns are dry-lined or plastered with a painted finish which is in accordance with industry standards.

Doors, Frames & Skirting
Skirting is formed of 100mm high MDF with a painted finish. Doors are solid core, timber veneered with painted frames and stainless steel ironmongery. The specification for these finishes is in accordance with industry standards.

Internal Conditions
Unless otherwise stated, all internal design temperatures are maintained within the range ±2ºC of figures stated:
Winter Summer
• Offices +/-2oC 22ºC 22ºC
• Stairs / corridors 18ºC no ambient control
• Toilets 18ºC no ambient control

Air Conditioning Load Allowance

• Lighting 12 w/m2
• Power 25 w/m2
• Occupants 14 w/m2

What this means in practical terms is that the air conditioning system in this property will cool the building to 22ºC on a day when it is 29ºC outdoors. This will vary from building to building depending on the design criteria and the geographic location of the building.

The system is not designed to cool a building to less than 22ºC on the hottest days. If the outdoor temperature exceeds 29ºC the building or certain areas of the building may not be able to be cooled as low as 22ºC.

During periods of cold weather, the system is designed to maintain a temperature of 22ºC. If the outdoor temperature drops to below -4ºC the building or certain areas of the building may not be able to be heated as high as 22ºC.

Mechanical Services

The heating and cooling system within the property is commonly referred to as a 4-pipe fan coil system. In practical terms, the heating, cooling and ventilation are all distributed by central plant, consisting of chillers, boilers and air handling units which serve all floors via the mechanical riser. The fan coil units are located within the ceiling void above the line of the suspended ceiling.

Conditioned air is supplied via the fan coil units where air is heated or cooled accordingly before being delivered to the office space via insulated ductwork connected to multiple slot linear diffusers positioned in the plasterboard margins around the perimeter of the floor plus a few swirl grilles serving central areas. Air is also re-circulated throughout the floor and the ceiling void is used as a return air plenum where conditioned air is extracted from the floor space via dummy sections of the linear slot diffusers and return air handling light fittings within the suspended ceiling.

Pipe Work Distribution
We are in possession of the mechanical services schematics and plans for the property.

Controls & Building Management System (BMS)
There is no facility for you to directly change the settings of the heating and cooling controls within the floor area, however, this would need to be carried out by the Building Management Team. The controls are fully automatic, interrogated and monitored via a remote Building Management System (BMS). The fan coil units have sensor phials connected to the return air plenums of each ceiling mounted fan coil unit and upon sensing a rise or fall in temperature from that set by the BMS the fan coil unit modulating valve will increase the chilled water or heating capacity as necessary and re-align the temperature to the floor.

Building Regulations require there to be ‘adequate means of ventilation provided for people in the building’. The requirements for fresh air ventilation rates are outlined in approved document F of the Building Regulations 2000. The purpose of ventilation is simply the removal of ‘stale’ indoor air from a building and its replacement with ‘fresh’ outside air. Despite pollution increasing levels of the regulations assume that the fresh external air is of a reasonable quality.

Within this property fresh air ventilation has been designed to provide 12 litres per second (12 l/s) per person based upon 1 person per 10m2. There is also an additional 10% for meeting rooms totaling 13.2 l/s per person based upon 1 person per 10m2. There is therefore an above industry standard of fresh air into the property.

The limiting factor of occupation for fresh air ventilation is therefore 89 persons. Only a very strong argument and in-depth discussions with Building Control will allow any deviation from this maximum permissible headcount when calculated against fresh air ventilation levels for the property. The provision of fresh air at 13.2 l/s per person based upon 1 person per 10m2 is a good allowance and meets with our expectations for a modern property.

Public Health Services
The following public health provisions are assumed to apply within the property, clarification should be sough form the Landlord to confirm these assumptions:
• The water storage has been designed to provide 25 litres per person
• Hot water will be distributed at 55oC
• Cold water storage temperature is less than 20ºC
• Hot water storage temperature is a minimum of 60ºC
• Hot water distribution temperature is 55ºC
• Hot water at accessible WC basins is 41ºC
• Rainwater collection and storm water drainage system complies with BSEN12056 Part 3 CAT 2
• Building fabric to withstand 100mm / hour storm

The above provisions are in keeping with industry standards.

Electrical Services – Design Criteria
• Standard power allowance for future tenant underfloor power – 25 w/m2
• Lighting allowance – 12 w/m2
• Spare capacity at riser – 10%
• Standby generator is provided to maintain life safety services in the event of a failure of the incoming supply and for the tenant’s essential small power use. This has been advised as 35w/m2
• The Landlord has advised additional power supplies are available at basement level

Electrical Services
The incoming supply to the building is taken from the sub-station established by EDF Energy in the basement. There are multiple electrical risers running up through the floors from the lower ground floor up to the 8th floor through the 4 no. cores. The core 3 riser has an 800 amp rising busbar system delivering 1 no. 400 amp 3 phase supply to each of floors 1st to 4th via a 315 amp fused tap-off units. All 4 no. core risers have a 200 amp rising busbar system, delivering 1 no. 100 amp 3 phase supply to each of floors 1st to 4th via fused tap-off units.

Lighting – Design Criteria
Lux levels are a measure of the level of lighting in a building or area of a building. The following lighting design criteria have been established for the property:
• Office areas 350 – 450 Lux at desk level
• Corridor / WC areas 150 Lux at desk level

The above design criteria are in keeping with industry standards.

A flex connector lighting system has been installed throughout the property that provides a flexible lighting solution. A network of 2-circuit linear busbar trunking has been installed within the ceiling void to provide power supplies to the lighting and fan coil units. Plug-in type flex connector Lighting Control Modules (LCMs) are installed within the ceiling void throughout the floor to provide plug connection locally of the lighting via 7-pin plugs. Supplies to the LCMs are connected to the 2-circuit linear busbar. Within this property, recessed 600mm x 600mm modular type lighting has been installed throughout the floor within 750mm metal tiles to provide LG7 compliant and energy efficient lighting. LG7 or rather lighting guide 7 is a CIBSE (Chartered Institute of Building Services Engineers) guideline for lighting.

Fire Alarm System
A fully automated addressable fire alarm system is installed to automatic detection covering all escape routes, rooms opening onto escape routes and areas classified as high risk in accordance with BS5839, as an L2 type (life level) system. The fire alarm system is common to the entire building, and comprises an addressable panel, fitted within the reception area. There are manual call points installed at each point of exit from the floor. Automatic smoke detection is presently installed to serve an open plan arrangement positioned at approximately 7.5m intervals.

Sounder bases are located throughout the floor to suit the open plan layout and would need to be modified and supplemented to ensure an average of 65 dB is achieved throughout the entire office space included as part of your fit-out.

Sprinkler System
The building is served by a sprinkler system compliant with BS5306 Part 2 1990 with OH1 hazard classification and life safety enhancement. We assume each floor has a separate zone valve with perimeter drencher system.

There is currently no data cabling installed throughout the floor. The floor has floor and ceiling access for the installation of your requirements and provides us with no concern regarding cable distances and system performance. The building is served by a dry riser compliant with BS5306 Part 1 for telephone and cable connections. A number of ducts are installed from the basement to the street to allow for future provision of telephone and cable connections by the tenants. Dedicated communications risers are provided with cable trays and cable baskets installed.

There are 6 no. 13 person passenger lifts, travelling at 1.6 metres per second with peak intervals of under 30 seconds. 1 no. lift is designated as a goods lift and we anticipate this can be utilised for the passage of materials providing adequate protection is applied to the lift and surrounding areas and all deliveries are coordinated with the building management. There are 2 no. additional fire fighting / passenger lift serving all floors in accordance with BSEN81-72

The property includes containment for future CCTV, intruder detection system, and access control. Wire-ways are installed adjacent each office entrance doorway and main reception doorway for future installation of access control, green break glass, and magnetic locks. This containment is taken back to the Building Manager’s office on the ground floor next to reception. Doors onto staircases have door access control already fitted.

Limiting Factors of Occupation
Property literature advises that the building has been designed to the following occupancy levels:

• General occupancy 1 person per 10m2
• Lifts 1 person per 12m2
• WC / bathrooms 1 person per 12m2 60% Male and 60% Female

A limiting factor of occupation is a statutory regulation that limits the potential headcount in a property.

WC / Bathrooms
As your bathroom facilities are shared for the most part (i.e. they are positioned in the Landlord’s common area allowing you to access WC / bathroom facilities on the lower floors), WC / bathroom facilities will not limit your occupancy of the floor,

Detailed appraisal of the limiting factors of occupation will assist you in identifying your occupancy levels and potential how these may be increased.


74,000 sq ft
Mourant Property Trustees Ltd
Recent refurbishment works completed in March 2013
Letting Agents
Strutt & Parker