Building case study -
“London City Hall”
Dr. Shaun Murray
Luigi Di Vito Francesco
Height of the building:
Gross floor area:
185,000 sq ft/18,000 sq m (approx)
No. of floors:
Net lettable floor area: Steelwork:
10 floors above the ground
130,000 sq ft/12,000 sq m (approx) Structural frame - 2100 tons
Reinforced - 1950 tons Concrete (core):
13,100 sq m
Average value= 0.7-0.8 W/m_.k
Diameter of glass facade:
Cladding: 7,300 sq m of triple glazed low emissivity coated clear glass, incorporating shading devices Angle of glass inclination:
Environmental strategy: Windows open for natural ventilation, bore hole water cooling, heat recovery, displacement ventilation system, no chillers required Architect:
Foster and Partners
The building is located in the London borough of Southwark, on the south bank of the river Thames. It is 45 meters high, with 185,000 sq ft (gross) of floor space spread over 10 floors. In conventional terms, the building has no front or back: its shape is derived from a geometrically modified sphere. This hybrid form is designed to minimize the surface area exposed to direct sunlight. The building has been designed to be as green as possible. Fig.2
Construction Managers: MACE
Structural, services, facade, fire, communications and acoustics engineers: Arup & Partners
Davis Langdon & Everest and Mott Green & Wall Townshends
City Hall is the headquarters of the Mayor of London and the Great London Assembly (GLA).
London City Hall is part of a development project on the South Bank of river Thames called More London; the project was developed by the architecture firm Foster and Partners. It includes the City Hall, 4 places, 4 buildings, a kiosk and a fire station. Many restaurants, cafes and shops are held in the 4 buildings.
The building is located in London (United Kingdom) in the borough of Southwark, on the south bank of the river Thames. The building is situated 5 minutes walking from London Bridge train and underground station. The closest bus stop (which takes the name of the building) is located within 3 minutes walking distance from the City Hall: buses 343, 47, RV1 and 381 and night buses N47 and N381 stop there.
The City Hall is part of a development project called “More London”, which was developed with the aim to give new life to the borough of Southwark.
The image below shows how to get to the City Hall walking from London Bridge station, illustrating the path I followed to get there once at the station.
Foster + Partners is a British architectural firm based in London. The practice is led by its founder and Chairman, Norman Foster, and has constructed many high-profile glass-and-steel buildings. Sir Norman Foster (Fig.5)
According to the architects, the building "expresses the transparency and accessibility of the democratic process and demonstrates the potential for a sustainable, virtually non-polluting public building".
The transparent glass exterior allows the citizens of London to feel like they are a greater part of their governing body. The transparent façade allows Londoners to see directly into the operating chamber, symbolizing an open system of government. City Hall design and symbolism was strongly influenced by one of Foster’s previous projects, the Reichstag Dome in Berlin. As for the City Hall, the Reichstag is symbol of transparency of the democracy and environmental sustainability.
The Reichstag (Fig.7)
The design for London City Hall was part of a developer-led competition, which asked for submissions according to a design brief that required the promotion of transparency and democracy. In addition to these requirements, Foster and Partners incorporated their own environmental goals for the project. In order to produce an energy-conscious design, architects began to collaborate with engineers, Arup, early on in the design process. Together, Foster and Partners and Arup worked to design the initial London City Hall submission, which took the form of a conventional office block with a debate chamber positioned at the end.
In order to achieve the goal of a green building in terms of energy saving the City Hall makes use of natural ventilation as major fons of ventilation.
Every office space has windows which can be opened manually to regulate the temperature of the room.
In summer the City Hall is kept cool through the use of groundwater which is pumped up via boreholes. During winter part of the air coming from the outside is used to heat the building.
After selecting Foster and Partners to take on the project, the jury, consisting of political and professional representatives, described the desire for a more iconic building form. With this direction in mind, the design team took the sketch that appealed to the jurors and began to reassess the presence of the brief requirements. As the design sequence progressed, the building began to take the form of a more dynamic shape that was conceptually driven by the detailed brief requirements.
Drawing showing the ventjlation in one of the offices (Fig.10)
CONVECTION Very important is also the function of the diagrid structure which doesn’t work only as structure but also as a radiator, as Arup stated:
Convection at daytime (Fig.12)
“The diagrid structure supports the north façade of the GLA building and is in fact the largest radiator in London. The majority of the horizontal steel elements, measuring a staggering 300mm in diameter each, have hot water coursing through them to act as a discreet heater for the atrium space that doesn’t require extra fittings or pipe work installation.” (Arup 2002)
The City Hall and generally the buildings located on one of the banks of river Thames benefit from the presence of the latter. This is because of the convection, which is the exchange of heat from a place to another one. Convection at night time (Fig13)
Light system has been studied and developed by the famous lighting company â€œClaude Engle Lightingâ€?, which has a strong and important portfolio which shows massive collaborations for important buildings such as Louvre museum in Paris or Reichstag in Berlin. The light system has been perfectly developed and is one of the aspects that make City Hall an innovative building. Natural and artificial light are perfectly mixed in the building.
The building might appears opaque during the daytime, but after the sunset light effects are very suggestive (see pictures below), .
Differently to most of the existing building the City Hall has been designed to be self-shaded. In fact thanks to its shape and orientation the building produce a very soft shadow at noon, while during the daytime shadow is a bit more evident. The drawings below illustrate how shadow varies according to daytime and season. Shadows on 21st June (summer solstice)
Shadows on 21st Decembet (winter solstice)
The building is 45 meters high, with 185,000 sq ft (gross) of floor space spread over 10 floors. In conventional terms, the building has no front or back: its shape is derived from a geometrically modified sphere. This hybrid form is designed to minimize the surface area exposed to direct sunlight. The building has been designed to be as green as possible.
Glass: this material has been used for the building facade mainly e many other parts of the building. Every glass panel is unique due to size studied at computer.
The building structure consists of a central tower made of reinforced concrete around which was constructed the rest of the building.
The building under construction (Fig.18)
The concrete core has an important structural function as it is the only vertical element that starts from the foundations and supports the loads of the upper floors.
Steel: the steel elements support the load of the building. An innovative technique called diagrid allowed the use of steel elements to support the glass panels which compose the facade of the building. Tiles: different floor tiles have been used in the different floors of the building. The 250-meter-long ramp is fitted with a nora rubber floorcovering. The floor is exceptionally wear-resistant, and eco-compatible, thus meeting Lord Fosterâ€™s wish for sustainability in the choice of construction materials as well. The rubber flooring contributes towards ensuring good acoustics. 15
USE OF MATERIALS
The building makes use of four different types of glass including double glazing and triple glazing used whit the specific aim to keep the building warmer, saving relevant quantity of energy.
London City Hall is one of the few building constructed using the diagrid (diagonal grid) structure. Despite other buildings here diagrid is used only to support the glass facade. This makes the City Hall a unique building.
The glass can be treated to make it more energy efficient, and the air gap between the glass panels can be filled with an inert gas such as argon, krypton or xenon, to help to reduce the heat loss.
Diagrid node (Fig. 23)
The diagrid structure has been used prevalently for todayâ€™s tall buildings worldwide. Diagrid structures create triangular with diagonal support beams. The pictures on the right show a diagrid node and the facade of the City Hall, built using Diagrid structure.
One aspect that is very characteristic of the building is the use of computer to create glass panels with the right inclination in order to make the building provide self shading.
Diagrid advantages Fig. 22
- Increased stability due to triangulation - Elimination of vertical columns
- ability to provide structural support for hundreds of shapes
- Reduced use of structural materials which translates into environmental savings
Diagrid disadvantages - Constructability is a serious issue in diagrid structures because its nodes are more complicated than those of conventional orthogonal structures.
- Reduced weights of the superstructure translates into reduced load on the foundations
USE OF WATER Water has a fundamental role in the buildingâ€™s HVAC system. The building is heated by boreholes, which reach 130 m down into the ground piercing the water table. These pump water up from the ground using photovoltaics solar panels power and circulate it round the building and are used for heating and cooling purposes. The actual system is incorporated into the structure of the building too which acts in saving space and materials because it works as part of the framework.
The water is pumped out of the ground at 12-14Â°C and then runs through the structural beams in the City Hall. In the hotter months this water is run through cooling coils, which are filled with cold air. This system cools the water that run through these pipes, this in tern is moved around the building cooling each room as it runs through.
During winter and the colder months the same process is replicated but the water is pumped through gas-operated boilers. Then through the same process, and through radiant heating, the water heats the rooms as it runs through them. Every office and the debating chamber are heated by convector heating using water from the boreholes. In a similar vein the heat from the computers and the operating systems is also collected. This is then used to re-heat the building. These methods are much more energy efficient and cheaper than typical routes used by other companyâ€™s. Although, this type of heating is rarely used in buildings as big as The City Hall as it takes a lot of money and time to originally set up.
ENERGY STUDY After being used in cooling and having reached a higher temperature the ground water is used to flush toilets.
London City Hall symbolizes modern architecture. Due to its egg shape, which has made possible a sensible reduction of the buildingâ€™s surface (about 25% less than the equivalent rectangular building), noticeable results have been achieved in terms of energy savings.
The rain water that is collected from the roof is used in toilets as well as non-potable water, after being used water is collected in a grey water tank.
The energy consumption has been greatly reduced by using ground water instead of refrigeration to cool the building. The installation of a new voltage system by Powerstar allowed a sensible reduction of the energy consumption of 13.6% as shown in the graph below.
A drainage system placed around the building collect rain water and re-use it in the fountains situated in the surrounding area.
Movement sensors (Simmtronic SPK28, in the picture on the right) have been installed in the building in order to switch off lights when nobody is in the office rooms. Fig. 29
The diagrams below show the heat loss by the building, the picture on the left helps to understand which part of the building we are talking about.
In 2007, solar photovoltaic panels were instled , generating energy for City Hall with zero carbon emission. The power from photovoltaics are used to pump water through boreholes from water table for cooling the building. The pay back for photovoltaics would extend well beyond 10 years, so they are not cost-effective. But the sun shading around the top floor could accommodate PV panels in the future.
Energy efficiency rating: D
Annual C02 emissions: 2,255 tonnes of carbon New buildings also fared badly, raising questions about the validity of sustainability claims made by architects and developers.
London’s City Hall, built in 2002, was described by its architect Foster & Partners as a “virtually non-polluting public building” has scored a D.
FLOOR TILES The designers decided to give the London City Hall an ecological with the aim to create an efficient political building symbolizing sustainability to Londoneers and not only.
For this reason the building show some very ecological solutions.
Recycled water, after being used in cooling the building, is used in toilets for flushing.
Great importance has been showed in the choice of materials. In fact many materials present in the building are recycled, proving again the attention of the designers to the ecologic matter.
There is some waste segregation and a small use of recycled materials, in mats and floor tiles.
The granite sand used for the Hal Mann’s ‘GLA’ flooring in this building was produced by crushing by-products left over from the processing of other products from solid granite slabs, such as kitchen and vanity tops. Larger granite chippings were also mixed in with the aggregate. The globigerina limestone sand was also a by-product from the quarrying of limestone blocks that are used to construct buildings on the island.
Nora rubber floorings from Freudenberg is used for floor covering in some areas of the building. One of the goals of the construction process is to minimise the burden of pollution on people and the environment as much as possible. For example, production leftovers are recycled, packaging materials are selected from an environmental standpoint, and floor coverings that are surplus to requirements are reused.
The building makes use of many modern technologies such as movement sensor and solar panels but still is not sustainable enough.
Personally I think that the solar panels are not very useful considering English weather, the panels will definetey not see a lot of sun during the year, excepr for summer-time.
One way to improve the building could be the use of wnd as energy source. The building is located a few steps from the river Thames and as seen at page, this means that there are air exhanges between the river and the surrounding area, so the power of the wind produced by exchanges of air might be used as fons of energy to make the building more sustainable.
London City Hall was built with the aim of being symbol of a sustainable city, which keeps evolving technologically but still cares about relation between man and nature.
Even if the building was built with the best intentions after more than 10 years since its inauguration it does not work really well and save far less energy than expected, basically because the number of people attending the building daily is much higher than what was established and thought at the beginning of the project. For this reason, even if modern technologies have been applied and are in use in the building, the City Hall cannot be considered an example to follow as it scored a poor D in the energy ranking (see page 24). Personally I think that the ony solution to the problem would be to be decrease the number of people working in the building in order to save more energy and be more sustainable.
As seen the introduction of solar panels and other technologies have not produced the effects they expected, so there is no need to keep insisting in using technology as it has been proven that it has not contributed much.
www.fosterandpartners.com/projects/city-hall/ www.london-se1.co.uk/places/city-hall londoncityhall.wordpress.com/
www.macegroup.com › Projects
http://www.londonheatmap.org.uk/Content/DHManual.aspx www.youtube.com/watch?v=uyiTALGMiJE www.london.gov.uk/mayor-assembly/gla
All the pictures not referenced have been taken with my personal camera. Figure 2 Source: http://www.ukh2mobility.co.uk/member/greater-london-authority/ Figure 3 Source: http://www.morelondon.com/
Figure 5 Source: http://www1.pictures.zimbio.com/gi/Sir+Norman+Foster+Norman+Foster+Press+Conference+DtTnAlBUBnYl.jpg Figure 6 Source: http://www.tctmagazine.com/downloads/1172/download/FosterLogoArt.jpg Figure 7 Source: http://thumbs.dreamstime.com/z/berlin-reichstag-dome-15560689.jpg Figure 8 Source: www.fosterandpartners.com/projects/city-hall/ Figure 9 Source: www.fosterandpartners.com/projects/city-hall/
Figure 18 Source: http://www.andrewrafferty.co.uk/products/steel-glass-and-people1/
Figure 23 Source: http://www.newsteelconstruction.com/wp/wp-content/uploads/2013/05/CheeseBoxMay13.jpg Figure 31 Source: http://ems-uk.org/gla%20graph%20v3.jpg
Figure 32 Source: http://www.simmtronic.com/switchplates/spk28
Figure 33 Source: http://www.theguardian.com/environment/2008/oct/02/carbonemissions.greenbuilding Figure 35 Source: http://legacy.london.gov.uk/images/city_hall/sp-013.jpg
Figure 38 Source: http://www.pharmaceutical-int.com/upload/image_files/articles/images/companies/1144/ FreudenbergArticle2Image2.jpg