When the RNIB refurbished an old building to create its new headquarters, engineers had to pay particular attention to occupant needs. We examine how the building services were designed to match these special requirements.
There is a growing emphasis in services engineering on meeting occupant needs. This is not simply about meeting the brief, but understanding the people who will work in the building, and engineering according to their personal and working requirements for a comfortable, usable and productive environment.

This was certainly the case for Silcock Dawson when it became part of the team to refurbish a building for the Royal National Institute of the Blind (RNIB). The building, on Judd Street in the Kings Cross area of London, was previously occupied by the Salvation Army. The aim of the refurbishment was to create a new headquarters for the charity which could provide over 4500 m2 of office space along with conference facilities, public access and areas for other specialist services offered by the charity to blind or partially sighted people.

Throughout the project, blind and partially sighted people and their needs have been central to design thinking. Paul Ross, partner at Silcock Dawson says: "It wasn't just a case of meeting the needs of the RNIB as a body. We got to meet key people, and were involved in many meetings with them. It wasn't just a case of doing a good job. We felt personally responsible because we were dealing with real people."

The man tasked with overseeing the project was Barry Gifford, financial director of the RNIB. He has experience of working in an international firm of architects and planners, so was well aware of the importance of conveying the thinking behind the new offices, as well as a detailed brief.

Thinking behind the project
"The services that we were providing to our customers or clients, couldn't be provided from our existing headquarters in Great Portland Street – nor could we add new services such as low vision facilities. We had been at Great Portland Street for over 80 years, in three buildings on many levels with about 130 very small rooms," explains Gifford.

"We also had one very grand room used for large meetings. But with the advent of technology, the heat generated by computer equipment had increased over the last three or four years, and with hot days in London it was intolerable for our staff and clients," he adds.

The RNIB had gained planning permission to convert the Great Portland Street headquarters into residential, which enhanced its value. However, the search for the new location took nearly four years. In order to ensure that everyone's needs could be met as closely as possible, the RNIB set up a series of groups which included a senior representative who would report findings and comments back to a Champions Group. The professional team was then appointed. "We took on Tilney Shane architects and interior designers to establish the core elements of how we might approach the building. They carried out a huge number of interviews with staff, customers, trustees and building users to find out what, in an ideal world, they would want," says Gifford.

The building
The three-storey building has its main entrance at the corner of two streets. The refurbishment of the old Salvation Army building was very thorough and consisted of gutting the interior of the building, including removal of an underground carpark, and the lift cores. The advantage of this approach was that it enabled the RNIB to effectively create its own space within the existing walls.

From an engineering point of view, removal of the car park created a comfortable space for a basement plant room – which makes a change from many refurbishments which often leave services struggling to find room for necessary equipment.

On the ground floor is a main reception, with seating area. To the right of this is a large retail area for RNIB products for the visually impaired, as well as a small research library. Behind the shop is a demonstration kitchen as well as an area where customers can try out computer equipment for blind and partially sighted people. Also on the ground floor are a number of consultation and counselling rooms.

The staff restaurant is on the lower ground floor along with a large conference room, while the cafe area is situated on the ground floor. One of the most unusual features is the dog loo, for the guide dogs of staff and visitors (with guide dogs).

The first and second floors and third have been planned with the same layout, to make location easier for occupants, both visually impaired and normally sighted. The building is a rectangle with an open light well in the centre. The offices are open plan around the perimeter with some offices positioned centrally, along with areas for noisier activities such as photocopying and the use of Braille machines.

Making it all work
Ross says: "From an engineering point of view, one of the key aspects of this project was creating a comfortable working environment, particularly in terms of temperature. The previous building had been prone to high temperatures and there was an issue with this. The brief wasn't specifically to provide a comfort-cooling environment, just a cool environment. Being a charitable fund, one objective was to keep capital and running costs to budget."

Silcock Dawson did model the building to operate with natural ventilation. "In many ways, the building suits that as it has the open light well, with lots of glazed areas so there is good scope for cross ventilation. No one is more than 6 m from an openable window," says Ross. The modelling showed that there were no occurrences of high internal temperatures, and they were significantly less than at Great Portland Street. "But there were instances where temperature could rise into the high thirties for periods. There was concern that the occupants would still experience the same atmosphere of the previous building."

The secondary consideration for natural ventilation was ambient noise level, which was surveyed day and night for seven days, internally and externally. It was found that with the windows open, the internal noise level would be unacceptable. "Where background noise to you and I may be acceptable because it isn't interfering, for someone relying on their sense of hearing, it is a much greater distraction," says Ross.

The engineers therefore had two drivers, pushing them towards the selection of artificial environmental control. "We did a series of presentations and reports and made the decision early on to go for artificial to achieve a reasonable degree of comfort. We looked at different options such as fan coil units, vav systems, as well as alternatives such as passive systems – chilled beams and chilled ceilings."

"It was eventually decided to opt for chilled beams. "We took this route because with fan coil units there was a noise issue. Most people wouldn't pick up on it, but to these occupants it would have been a significant noise.

"Also fan coil units, whether in the wall or ceiling, require regular maintenance – filters require changing. This means maintenance operatives would be working in the space which creates obstructions and risks with stepladders and so on," comments Ross.

He adds that there were also physical issues, with the building not designed for air conditioning. "We also have high ceilings and large windows here, which means lots of natural light. To introduce a dropped ceiling would have spoiled the atmosphere and created an almost old-fashioned working environment."

The chilled beams also had energy and cost savings advantages. Ross comments: "The beams have no moving parts and only require a once a year wipe down. There is an operational saving as well as potential running cost savings with possible free cooling in Autumn and Spring. They are also virtually silent in operation and suited the interior design."

Chilled beams are used on the first and second and third floors, but vrf air conditioning is used on the ground floor and lower ground.

Sounding it out
For blind and partially sighted occupants, the issue of sound is important as they are sensitive to noise which others may not pick up. Also, some occupants are deaf as well as blind. Ross says: "We took a whole view on acoustics, as it's one area we are going to get a lot of feedback on. We worked with the architects on the building layout. For example, we made sure we moved the noisy operations such as Brailling away from working area. Photocopying areas are separately partitioned. We also looked at finishes and managing noise transmission. The staff were also sensitive to noise because they were going from closed offices to open plan. "

Lighting
The key challenge for lighting was that individuals have very different requirements. For the visually impaired, lighting needs can vary widely – some are sensitive to light and need lower levels, others prefer much higher than normal lighting levels. To overcome these issues, Silcock Dawson used the latest in intelligent lighting.

"We used digital ballasts on light fittings, a Dali system. The fluorescent tube is normal, but they have an intelligent, addressable ballast on the end. By linking all these ballasts together, with a simple two-core communications cable, through the control system, we can vary the output of that fitting almost infinitely," says Ross.

The intelligent lighting can vary from 100 lux to 1000 lux. The lighting can be controlled either by plugging a laptop into the main system and doing it centrally, or it can be altered using a hand-held device. Conference rooms have more traditional dimming systems switched locally.

"We have created a very flexible lighting system. It was a higher capital expense, though not as much as you might think. That is really the way forward for office lighting. You're using two-core cable so installation is relatively low-tech and simple. They are standard fittings and tubes, and it is low maintenance. The technology is in the factory. It helped greatly on a refurbishment like this."

Keeping end users in mind
The services engineers and others on the team have worked to create an environment suitable for occupants and visitors with very specific needs.

The advantage has been that the project has been overseen by a client with a good understanding of the benefits of a high quality brief, and of including engineers in discussions from early on in the process.

The RNIB has unique qualities as a client, not least a very long-term view. Barry Gifford comments: "The quality of the building must be very high; something we can justify as an investment. The RNIB will probably be here for 100 years – it's a long lease. So we are investing as our predecessors did in Great Portland Street."

Mechanical suppliers

AHUs: Delrac (Wolf)
Air curtains: Envirotec
Anti-vibration mounts: IAC
Boilers: Viessmann
Burners: Riello
Ceiling diffusers: Gilberts (Blackpool)
Chilled beams: Halton Products
Chillers: Delrac (Multiclima)
Control valves: Trend/Samson
Computer room a/c: Daikin
Dampers: Actionair
Dry riser inlet boxes: Angus Fire Armour
Ductwork: Hotchkiss
DX systems: Daikin
Extract fans: Nuaire/Vent Axia
Expansion bellows: IAC
Flues: Selkirk
Grilled tube: Unilock HCP
Hot water calorifiers: Heat Transfer
Humidifiers: JS Humidifiers
Insulation system: Kingspan
Louvres: Gilberts (Blackpool)
Pumps: Holden & Brooke
Pressurisation: Holden & Brooke
Radiators: Bisque
Raised floors: Hewitson
Sound attenuation: Sound Attenuators
Strainers: Holmes Valves
Tanks: Balmoral
Toilet extract: Nuaire
Water treatment: Hydrotec
Valves: Holmes Valves
VAV boxes: Halton Products

Electrical suppliers

BEMS: Palcon Systems (Trend)
CCTV: ADT
Cable management: MK
Communications: Entropie
Controls: Trend
Electrical distribution: MK
Electrical accessories: MK/Hamiltons
Fire alarm/detection: ADT
Floor boxes: Electrak
HV switchgear: Merlin Gerin
Lifts: European Lifts
Lighting controls: Helvar
Luminaires: IBL
LV switchgear: Merlin Gerin
Motor control centres: Palcon Systems
Power busbar: Electrak
Public address: ADT/Clarity
Trace heating: Jimiheat

Engineering data

Gross floor area (gfa): 6250 m2
Net usable area: 5000 m2
Plant rooms: 200 m2
Offices: 4492 m2
Computer suite: 108 m2
Amenity & dining: 200 m2

Contract details
Tender date: October 2000
Tender system: Single Stage Traditional
Form of contract: JCT 98
Contract period: 16 months

External design conditions
Winter: -3°C/100% Sat
Summer (a/c): 29°C db, 23°C wb

Internal design conditions
Winter: 21°C min, % rh
Summer (non a/c): max 27°C
Summer (a/c): 23°C ±2°C, 40-60% rh
Circulation & toilets: 27°C max, 21°C min

Structural details
Clear floor void: 150 mm
Floor to ceiling: varies 2·4 m minimum to 3·2 m max
Ceiling zone: varies 100 mm to perimeter, 1000 mm in services spine

Occupancy
Offices:1 person/10m2
Meeting rooms: 1 person/7 m2

Noise levels
Offices: NR 35
Toilet & circulation: NR 40

Target energy use (gfa)
Gas: 97 kWh/m2/y
Electricity: 110 kWh/m2/y
CO2 target: 19 kg/m2/y

Energy breakdown
No figures yet. Building is being monitored by bems for first year and adjustments made to control routines as we go. Was BREEAM used: Currently under assessment.
Rating: Very good is predicted in pre-assessment checks. Loads
Calculated heating load: 720 kW
Installed heating load: 900 kW
Calculated cooling load: 570 kW peak
Installed cooling load: 542 kW with thermal buffer
Equipment: 20 W/m2
Lighting: 12 W/m2
Occupancy: 10 W/m2

Ventilation
Scheduled supply air temp: 16°C to beams and 21°C elsewhere
Fresh air: 12litres/s per person
Filtration EU category: EU7

Distribution circuits
LTHW: 82°C flow, 50 °C return
DHWS: 65°C flow, 60°C return
Chilled water: 8/13°C primary, 14/16°C to beams
Refrigerant: R407c

Electrical supply
kVA transformers: 1 x 1000 kvA
kVA ups system: none
kVA standby power: none

Lighting
Types: Flourescent T5 up and down lighting
Lux levels
Office: variable 100 lux to 1000 lux
Conference: variable 100 lux to 1000 lux
Kitchen: 500 lux
Computer: 500 lux
Toilets: 350 lux
Stairs: 350 lux
Circulation areas: 500 lux

Costs
Total cost: £6 million
Building services total: £2.3 million
Total net cost (£/m2): Services £460/m2