The particular project I am looking at is a College in Westminster, London. The main aim of this project is to provide further education for students in the City of Westminster Borough. This college is a very important project as it is considerable different to previous buildings in Westminster.
When constructing a new building it is important to consider the occupants needs, please see Fig.1 (taken from Powerpoint presentation Construction Tech B Lesson 1) below indicating the generic requirements of all buildings.
It is important to note that all of the above requirements are essential for any new building. However, the basic requirements for Westminster College in which I am going to focus on are appearance, security, sanitation, thermal/lighting comfort, weather exclusion, and an in depth look at fire protection.
When considering the appearance of this college building it was important that it stood out as according to the McLaren Construction website “This stunning landmark building is regarded as the LSC’s flagship project and will act as a benchmark for future college developments across the UK.” Please see Fig.2 for external design picture of the building taken from the McLaren website.
I consider this buildings appearance to be very modern in terms of current fashions within the industry at present. The large amounts of glass and modern method of construction in terms of curtain walling and steel frame means that the construction of the building looks more “high tech” and futuristic in terms of appearance. This will cause it to make a statement as it is located in the middle of a more traditional constructed area around Paddington Green.
Obviously being an education facility the security aspect of the building is very important. When considering the external facade all the curtain walling has lockable double glazed aluminium windows and doors. Furthermore all internal and external doors are lockable via an access control card system. See Fig.3, drawing produced by Schmidt Hammer and Lassan architects for the project.
Furthermore when students are to enter the main entrance of the building this is controlled by card accessed turnstiles. This will prevent anyone without a card access. Also all entrances to the building have a security camera installed which will record the data onto a hard drive in the Security Office. This is then backed up twice a day via an external server.
With regards to the sanitation this buildings has to offer, there are three cores of toilets per floor. Within these cores male toilets contain 3 cubicles, 4 urinals and 5 sinks, female toilets contain 6 cubicles and 5 sinks, disabled toilets contain 1 large sink, 1 toilet all associated Doc M fittings and a lockable entrance door. Furthermore in these cores is a janitors store room and a cleaner’s cupboard with a large Belfast sink and shelving. Also within the gym and sports hall areas there are large changing and washing facilities which are separate for male and female, including shower & toilet cubicles, sinks, lockers and benching with attached pegs.
When looking at the comforts required for the occupants within the building, lighting and heating spring straight to mind. Within Westminster College the air conditioning system is the primary form of temperature control within the building. To help this work effectively the building has very good insulation and draught proofing which reduces the heat lost from the air-conditioning system. When considering the lighting system it is essential to provide the required levels of lighting internally known as Lux levels. Furthermore when considering lighting it is essential to have an emergency lighting route to ensure the occupants can safely escape in the event of a failure of the main lighting system and a backup generator to ensure the electricity to the building is retained.
The building envelope provides protection from the elements. The facade itself is a predominately a curtain walling system with all the windows and doors double glazed. The envelope prevents penetration of the elements including wind and rain. By installing excellent insulation and double glazing maintained the human comfort element by insulating the building envelope.
It is essential that a construction project like this has good fire warning and protection as vast amounts of students will be using the building and facilities. Furthermore a serious issue within the education sector is the risk of arson, again re-iterating the need for a good fire protection system. The main considerations of fire protection within this particular education project are; means of warning and escape, smoke clearance, compartmentation, internal fire spread, fire fighting access and Facilities and fire safety management.
A fire detection and alarm system is of great value in the event of a fire. It’s essential that all escape routes have some sort of detector. In this project point source smoke detectors are in most areas throughout the college. In areas where the risk changes such as workshops and kitchens an alternative detector called heat detectors are used. Finally in areas people with hearing impairments could be alone such as toilets the detector is to incorporate xenon flash tubes. Furthermore beam detectors will be provided in the atrium space so that regardless of which floor students are on the beams of light are easy to see.
According to recommendations by FEDRA manual call points forming a fire points are required. (Located on the website http://www.burohappold.com/BH/Home.aspx accessed 7th December 2009)
The fire points are to consist of:
ï¿½ A break glass manual call point,
ï¿½ Emergency lighting,
ï¿½ First aid fire fighting equipment,
ï¿½ Escape signage,
ï¿½ Procedures on what to do if discovered a fire, and
ï¿½ Telephone numbers for the Facilities Management.
Reference (66 words)
This means should any occupant of the building notice a fire which hasn’t been detected they will break the glass setting off the alarm. The alarm has a panel situated within easy access for fire brigade personnel. This panel is to be located on the ground floor behind reception so staff can respond immediately to the alarm. However, this building has a fire command centre due to its size and intended usage. This is a protected room on the ground level providing facilities for the fire service.
The concept behind the means of escape is that occupants should be able to turn their back on a fire and escape safely. They should be capable of achieving this in a limited distance specified for particular building uses. Furthermore there is a designated escape route on each floor leading to the staircores and out the fire exits.
The escape route is indicated using emergency lighting and wayfinding signage. The reason for emergency lighting is to ensure the occupants can safely escape in the event of a failure of the main lighting system. Furthermore all routes leading to emergency exits will be marked and visible by the use of the wayfinding signage so occupants can identify their most appropriate route to an assembly point in case of emergency.
When considering how smoke produced in a fire is to be released from a building there are mechanical and natural means in which this can be achieved. When looking at Westminster College they have a combination of both concepts.
Firstly smoke extract fans were utilised ensuring the fire rating of the fans were capable of handling extreme temperatures for one hour minimum and are able to extract a certain amount of smoke per m3 per second. Also on this project mechanical automatic opening vents (AOV) are utilised, so should there be a fire detected these vents will open allowing smoke to be drawn up through the void and out via hood on the roof.
For any smoke removal system to work effectively it requires a source of replacement air. The replacement air can be supplied either naturally or mechanically. Generally on this project the source of replacement air was via natural sources. In the entire curtain walling trickle vents are designed to remain open allowing natural air to come. Also vast amounts of curtain walling have large opening windows which can be manually opened to provide more airflow.
When looking at ways and areas in which a fire will spread inside the building there cavities in which fire can penetrate and spread through. For example through open doors, walls, ceilings and voids. Therefore precautions in these areas needed to be addressed to reduce the risk and speed in which fire will spread.
When considering doorsets at Westminster College the majority of fire rated doorsets were to achieve FD30 rating. It is important that if the fire resistance of a whole partition is 30 minutes both the wall and doorsets need to ensure that the integrity of the partition achieves its requirements. When the door is to be fitted on an escape route or to a riser door the doors were FD30s doors. For a door to achieve an FD30s rating, intumescent strips with smoke seals are fitted into the frame around the 3 sides of the door. In case of fire these strips expand forming a closed gap around the door preventing fire penetrating for 30 minutes. Also all fire rated doors must be fitted with a self closing device, in this case surface mounted overhead door closers are utilised.
The choice of materials for walls and ceilings can affect the spread of a fire and its rate of growth. On this particular project there are vast amounts of timber panelling to circulation areas. It’s essential these particular linings reduce the spread of fire within the building as much as possible. Therefore it was decided these panels where to be constructed using Class “0” fire resisting substrate and lacquer.
Furthermore to prevent the fire spreading around this building it was decided in cavities, 30 minute fire-resisting barriers are placed at regular intervals throughout the building. The maximum length of the cavity barriers is 20m.
Finally, an automatic sprinkler system was installed throughout, so should there be a fire the water released should help to put the fire out. In certain areas such as plant rooms which contained water sensitive equipment alternative suppression systems are currently being considered.
Furthermore another important fire fighting concept used on this project was dry riser inlets. These are located so they are easily identified via appropriate signage by the Fire Service upon arrival on site. Also the pump appliance should have direct access within a certain distance of the inlet.
When the CDM Regulations were reissued in 2007 far more importance was placed on designing out potential risks at the design stage of the project. Furthermore as the project progresses designing out the risks isn’t just the responsibility of the designers it also falls onto the contractors and the client to ensure that risks to operatives and occupants are reduced.
The HSE website states that:
CDM 2007 will help you to:
* Improve health and safety in your industry
* Have the right people for the right job at the right time to manage the risks on site
* Focus on effective planning and managing risk – manage the risk not the paperwork
Reference (53 words)
The main difference to the updated regulations is the involvement of the architects and designers. Previously the architects drawings tended to reflect an aspiration of a design regardless of buildability. Now since these updated regulations have come into force they have responsibility to ensure that the design incorporates easily maintainable concepts for the occupants and is safe for construction.
It is important when designers are designing a building to consider particular types of materials which are safe and easy for the occupants to maintain. For example if a building has a considerable quantity of high level glazing, this can be difficult and costly to clean. Therefore by specifying self cleaning glass albeit it may be more expensive at the outset it will not cost to clean and prevents the risk of danger whilst cleaning.
When considering the City of Westminster College project there was couple main changes which were introduced by the designers and construction team to conform with the CDM regulations whilst the project was being constructed and maintained.
Firstly at design stage it was decided that due to the entire external facade being constructed using aluminium framed curtain walling that the cleaning and maintenance of this glazing could become problematic. Therefore it was decided that the glazing was to all be a self cleaning system by Schuco. This meant that the risk from working at height when the windows needed cleaning has been eliminated.
Furthermore within the college there is large atrium throughout the centre piece with glass balustrade over the void. This again posed a problem with regards to maintenance. However as this glass in theory was not required to be cleaned as often the designers went for a different solution. It was decided to bed large steel hooks into the concrete so that when the glass was to be cleaned the cleaner could fix a harness to these hooks. This concept did not completely eliminate the risk however it does reduce the risk whilst cleaning
The final concept decided was to utilise pre-fabricated building materials where possible. When considering off-site construction health and safety risks on site are vastly reduced as products which are manufactured off site are made in controlled and safe surroundings. Also it reduces the amount of work and time for the product to be installed on site hence this can reduce the number of operatives required on the site at any one time. This causes the risk during installation to be reduced on site due to being quicker to install and the reduced amount of operatives on site again will reduce the risk during site works.
In conclusion CDM regulations have formed an important part of the construction industry since being introduced they are there to help make the construction industry safer for operatives and the end user of the building.