ARCHITECTURAL DESIGN COMPETITION FOR THE PROPOSED DEVELOPMENT OF GHANA NATIONAL PETROLEUM CORPORATION (GNPC)
NEW CORPORATE OFFICE AT ACCRA
1 - DESIGN CONCEPT Our concept scheme for the GNPC new office building in Accra incorporates the latest trends in office design. In the "era" of the information as main growth driver, the main objective in a modern concept design for office buildings is to provide a corporation with a headquarter where communication between employees and management and employees is easy and immediate. All departments need to be in connection and capable to deal together in order to proceed successfully. Lacks in communications cause large losses to companies and corporations. This is why the latest successful schemes in office design tend to facilitate people relations and exchange of information thanks to connections in between the different departments, common space for interactions, facilities for gathering and creating strong feeling of group identity. The second relevant element is space quality in relation to the work environment and the occupant wealth. This means work spaces implemented with climatic control, indoor air quality, views towards the outside and vegetation, plenty of open space and natural daylighting. Our design keeps into account these issues related with interior spaces and conjugates it with sustainable solutions and innovative design in the physical form.
The result is an "open" building where outdoor space and vegetation are arranged to penetrate the building envelope and maximize landscaping features and pleasant views. In the form configuration the first macro-concept that we consider is orientation: we set the building main facades with glass surfaces on the north-south elevations. This is the optimum in order to maximizing daylighting in the interior workspaces while protecting accurately the glass surfaces from strongest sun-radiation. Our strategy is to provide outside views as much as possible while protecting the building envelope exposed to strong sun radiation. This includes the building top surfaces. In order to do so we designed a large "umbrella roof" to create a wide shading to the whole building. As per building orientation we got to divide the massing in two parallel blocks in order to have 4 main facades with good exposition.
The two blocks represent the hierarchy of the corporation where the two main groups of functions are the "Operations" and the"Administration". Each one is hosted in one of the two blocks. The blocks are then connected by a large lobby on the level +1 and "meeting bridges" or flying over corridors. We conceived these meeting bridges as common meeting spaces that can be used by single Departments or even shared by different Departments and represent the point of junction of the whole company between the Operations and the Administration that includes the Management.
The position of the two building blocks are switched so that on East and West side of the plot we create a car driveway with parking spots and a pedestrian plaza respectively. The Entrance is set on the East side and the position of the two building blocks allows an extremely modern/monumental foyer, covered by the overhanging roof and that generates a spacial East-West axis through the whole complex: is the "galleria". The galleria is conceived to be the "communicational" corridor that connect the whole workspaces of the building and where the entrance lobby is located. This lobby connect the two blocks at the ground level and maximize circulation and distribution of the workforce in the building. It is a centralized point of control that increase security in the building.
Both car and pedestrian entrance to the building are located on the East side by the secondary road. This is in order to have a correct circulation and driveway access in both ways and a regular flow of users in and out the complex without consequences on the city traffic. Security checkpoint is also centralized on the main gateway on the East side. The driveway is arranged to allow car traffic in the complex smoothly. A covered drop-on/off, proximity parking spots and/or ramp down to the 3 stories parking garage are the options. The rest of the complex is car/free. This would minimize the impact of driveway infrastructure such as asphalt areas, roads on the complex and reduce the heat island effect nearby the building. Clearly gained outdoor areas are used for landscaping and vegetation so implementing the beauty of the whole construction. The building is 10 story high above grade and has a 3 stories parking garage below grade.
The "Operations" block is conceived as a monumental stone volume while the "Admin" block is a transparent fluid-like-oil volume which is connected to the "Operations" throughout bridges at all floors.
A large metal flat roof is supported by the stone block and covers both blocks in order to both create unity and protect the complex by rain and extreme sun radiation. On the West side of the complex there is a pedestrian plaza for gathering and outdoor lunch break. Moreover this is the area used for outdoor the company kindergarden which is located in the North/West wing of the building. There is an Attic on the building with outdoor roof garden. This is a facility for marketing events or reserved parties and meeting. Part of the Attic is covered and shaded by the umbrella roof. Glass front on the South elevation is fragmented so that each building story is set as an individual element.
This gives the building a vibrant effect of complexity and cooperation, innovation trends but strongly dependent from the solid standing of the other facades in stone panels with austere monumental windows opening which represent the established institution and its traditions. In the indoor side we favored open spaces and double heights in order to increase connectivity within the company personnel and therefore exchange of informations. We also alternate open spaces and single office rooms. The social common areas are widespread through all the building and in part concentrated in the two stories podium, including the conference hall and cafeteria.
2- SCHEDULE OF FACILITIES AND SERVICES The project proposal offers facilities in addition to the requirements for design report. These function provide facilities for a modern use of an office building.
STRUCTURAL SPECIFICATIONS 4.1 General Schemes The building has three underground floors, made entirely of reinforced concrete, and 9/10 floors above ground most of which is made of steel. In fact, apart from the rigid walls made entirely of reinforced cement, a metal frame will be used for the pillars and beams. The structure of the floor slabs will either be made of steel and concrete, or only reinforced concrete, depending on the technology adopted to ensure the performance characteristics required to meet the comfort parameters of the building (building used as an “administrative centre / offices”: acoustic isolation between floors, vibrations, etc.). The seismic action has been assessed using the seismic hazard maps for the site where the building is to be constructed; these maps are provided by NASA and are equivalent to the seismic ground motion value cited in the geological report attached to the tender.
The “compensated” foundations will probably be superficial since it is possible to exploit the three underground floors to compensate the weight of the building above. However, based on a much broader and in-depth geognostic campaign, pylon foundations may be chosen during later design stages. Construction of the underground floors will require retaining structures which will play both a temporary and permanent role: a “top-down” criteria will be adopted for the construction of the floors exploiting the floors themselves as stays, also temporarily, to support the shoring walls. Apart from the preliminary assessment of the weights and permanent loads which will depend on the typologies chosen during elaboration of the final design, for accidental loads we have adopted the values normally used for “office” buildings based on the recommendations by Eurocode. The structures of the building have been designed using antiseismic criteria as well as the usual “good building” rules relating to housing types. The structural framework has been designed so that the interaxes of the columns are compatible with its use as offices, and yet also provide maximum flexibility should the workspace be redesigned in the future.
4.2 Reference standards Eurocodes have been taken as the basic reference standards, in particular: • Eurocode 1: Actions on structures; • Eurocode 2: Design of concrete structures; • Eurocode 3: Design of steel structures; • Eurocode 4: Design of composite steel and concrete structures; • Eurocode 7: Geotechnical design; • Eurocode 8: Design of structures for earthquake resistance.
4.3 Calculation model The calculation model used to determine stress and deformation considered possible interaction between the two blocks due to the flying bridges and technical roof floor. The calculation programme MIDAS Gen 2015 v1.1 was used to study the model. The steel and concrete members have been modelled using one-dimensional beam type elements. The elevator blocks have been modelled using two-dimensional plate type elements (shell).
The constraints at the foot of the pilasters and perimeter wall are fixed joints. Here are some of the images taken from the graphical output of the elaborations relating to: - the undeformed structure; - the initial shaking modes; - the stress of the rigid walls when horizontal action is applied; - the deformations corresponding to seismic actions; - the reactions at the base.
These assessments are in line with the ones envisaged for a preliminary study, however they were performed to verify that the hypothetical structure be within the feasibility margins required for this kind of building.
5 - MECHANICAL /ELECTRICAL/SECURITY/EQUIPMENTS/FURNITURES/ICT 5.1 General notes All mechanical, electrical, security, fire prevention and furnitures, moreover ICT and all the engineered solutions proposed are based on the LEED Certification system ( Leadership in Energy and Environmental Design ) and subject to the rating from this Institution. LEED is already a philosophy in design and which is present at the earliest stages when the building is conceived and designed. All systems are conceived to be sustainable and have management controls and zoning in order to maximize functionality and cut operations and maintenance costs.
An overview of the main solutions to be adopted is listed below:
5.2 Energy & atmosphere - Fundamental refrigerant management. The use of the R401 gas in the heat pumps, for heating and cooling the fluid that goes into the air treatment plant batteries (HVAC), needs some particular precautions for the maintenance operator. Indeed, the R401 gas is a greenhouse gas and for this reason it must be managed with the following measurements:
1. Ensure proper installation and maintenance of the equipment hold by specialized companies; 2. Prevent and repair losses as soon as they are revealed; 3. Control the gas losses with a monitoring system , and once the maintenance company finishes to repair the damage they must do a leak test with a dry gas suitable for the pressure test; 4. Install appropriate detection systems as close as possible to the compressor; 5. Recover the refrigerant before the final disposal of the equipment and, if possible, during the normal maintenance operations.
5.3 Indoor environmental quality - Minimum IAQ performance The comfort of the people (thermal comfort and air healthiness) is entrusted to a HVAC system that will control the changing of the air while conditioning, cleaning, heating, cooling, humidify, dehumidify, and local controls of the air itself. This will create comfort areas for the people that will work in the offices. The choice of a system that can recirculate the internal air, and with the use of a heat exchanger between the air that comes from outdoor and the internal air, can guarantee the perfect indoor comfort for the offices, lowering the costs of air conditioning.
5.4 - Environmental tobacco smoke control Smoke is a risk for all workers and expensive for the employer. Protecting workers health from risks associated with smoke can take place by creating smoking areas so that the non-smokers will not share the same spaces. These areas will be bordered and outside these areas it will be all non-smoking. The smoking area will have some requirements: “bottom-up” boundary on all four sides, automatic closing door, ventilation, filtration, no recirculation of the exhaust and if the ventilation system is out of order than the smoking room must remain closed until the damage will be fixed.
Therefore, tackling with the smoking problem the solutions are forward: 1. Promote the respect of the non-smoking areas to safeguard the non-smoking workers; 2. Discourage smoking in all workers.
5.5 - Outdoor air delivery monitoring The principal point of this task is to reduce the pollutants in the outdoor air emissions. A first way of achieving this goal is to install separate exhaust systems in areas with high indoor air pollution sources such as kitchens, janitorial closets, photocopier areas, and office equipment rooms.
5.6 - Increased ventilation With dedicated and controlled ventilation air fans and dampers and/or dedicated ventilation distribution, the quantity of air can be regulated, measured, and documented. This provides greater certainty that acceptable air ventilation is maintained. Ventilation air can be separately conditioned for improved energy efficiency. In the offices it will be possible to regulate quantities of ventilation air based on specific occupancy needs. For example, sensors that detect occupancy, carbon dioxide, and volatile organic compounds (VOCs) can be used to monitor occupant loads and provide greater freshair intake. Consider air cleaning with high-efficiency filtration.
5.7 - Indoor chemical & pollutant source control It is true that recirculating indoor air the costs of air conditioning are lower, but it is easy to encounter the problem of the concentrations of the pollutants. It will be necessary to filter the air that we will recirculate to avoid such problems and mixing this air with fresh outdoor air. Afer mixing the two airs they will be filtered again inside the HVAC system.
5.8 - Thermal comfort, design & verification Thermal comfort is accomplished by regulating air temperature, radiant heat loss or gain, solar heat gain, relative humidity and air movement. There are many factors that have been considered while designing the thermal comfort of this project: recognize climatic concerns of the region, acknowledge impact of the orientation on the building, configure the envelope to deal with the conditions created by different orientations and to minimize conditioning loads. Elements within the wall, roof or floor have been designed to include adequate insulation to ensure thermal comfort but also a vapor barrier because the effects of moisture migration are not often felt by occupants directly, but can greatly affect the longevity of an enclosure system and the entire building. Mechanicals systems are an important component in creating thermal comfort and good indoor air quality, in such mean they have been considered and designed. The goals achieved have minimize loads with the mechanical systems by optimizing orientation and envelope design and organize interior spaces and locate equipment in order to minimize loads. The direct control of the indoor environment (temperature and humidity) occurs trough a HVAC system, in this case with a recirculating indoor air system to recover the cooling/heating of the indoor spaces before expelling the air outdoor. The room sensors will be placed in specific points in order to detect variations of humidity and temperature respect to the project values, and will launch a signal to the HVAC system in order to fix the indoor air quality and conditioning. All the HVAC system will be integrated in a building energy management system to monitor and optimize system performance.
5.9 - Sustainable sites Stormwater desig, quantity control Basic components of a rainwater-collection system include the catchment area (the roof), conveyance system (guttering, downspouts, piping), filtration system, storage system (cistern), and distribution system. The roof is made using appropriate materials, gutters and downspouts are sized for the roof size and rainfall intensity. After collection, the water will be used in the irrigation system and in the toilet-flushing systems. In this case there are 4 cisterns of 20.000 L each disposed in the first basement level. From this cisterns a hydraulic pumping system will manage the circulation of the water to the irrigation and to the toilets-flushing.
5.10 - Storm-water design, quality control Simple filtration with graded screens filters harvested rainwater for use in irrigation and in the bathrooms.
5.11 - Water efficiency Water efficient landscaping, reduce by 50% To reduce water landscaping losses it will be adopted the following measures: 1. after disturbance, native plantings were restored by reintroducing the same species; 2. minimized use of high-maintenance lawns; 3. minimized use of annual plants, because annuals require more irrigation than perennials.
5.12 - Water use reduction Faucet bubblers and flow restrictors further are disposed to reduce water consumption. Separate and use graywater generated from indoor uses such as sinks can be reused in toilet flushing or irrigation through the installation of dual plumbing lines in buildings interiors. Graywater irrigation system is composed by: a separate tank, filter, and special emitters.
5.13 - Controllability of systems, lighting The designer has established required illumination levels, to meet the needs of the building occupants and the tasks they perform, applying some general daylighting principles: avoid excessive brightness; utilize plants, draperies, screens, translucent shades, and light-scattering glazing’s because they diffuse and distribute light while reducing its intensity; utilize an appropriate room reflectivity (surface reflectance), rely on clerestories in addition to windows. In addition, lighting controls integration will automate the reduction of electrical lighting operation and control lighting to respond to levels of daylight; scheduling controls, occupancy-sensor controls and lumen-maintenance control programs will allow a better daylighting-control.
5.14 - Construction IAQ Management Plan, during construction To avoid indoor contamination during construction activities it as been considered an IAQ construction management plan. In this way it will be possible to identify potential health hazards (dust created by the disturbance of building materials, emissions of volatile organic compounds (VOCs) from materials and products and also emissions of combustibles and VOCs from construction equipment or construction processes) and take necessary safety precautions. Barriers with ventilation measures will be used to prevent the migration of airborne pollutants from areas under construction; in addiction, ventilating the building during the application of wet products, will reduce contamination as such materials emit high levels of VOCs.
5.15 - Construction IAQ Management Plan, before occupancy To expel contaminants, air shafts, areas that will be occupied and all finish materials will be cleaned with high-efficiency particulate air (HEPA) vacuum equipment prior to occupancy to remove dust and debris. Mechanical system will run with tempered 100 percent outside air for an extended period of time after construction completion and prior to occupancy.
5.16 - Fundamental commissioning of the building energy systems Construction-phase and post-occupancy building commissioning improve the building systems performance under real, live conditions, reducing the potential for user complaints.
During construction-phase will develop a strategy to implement the building-commissioning process: form a commissioning team and designate a commissioning authority, design team and building operators review the documents to confirm that the building is properly designed for its intended uses. The design team will be involved in monitoring the construction commissioning process to verify that construction is in accordance with the contract documents. Energy systems and equipment startup will be performer and when the commissioning process is complete, the commissioning agent should issue a commissioning report to the owner. Ended construction-phase, during post occupancy and after one year, fine-tuning of building systems and equipment it will be conducted, this will allow to solve any building problems identified. After this first year, recommission buildings throughout their life will be done on a regular schedule, possibly every one to two years.
5.17 - Green power Passive solar heating (direct gain through south-facing glass) will be installed on the roof to manage hot water to the toilets and kitchens. The solar heating panels will heat 8.000L of water stored in boilers on the roof. From this point hot water will be taken down to the single needs with a hydraulic pumping system. It is suggested in the design a photovoltaic system of about 300kW, that will be used for the building needs. HVAC system uses electricity, al pumping systems use electricity, and therefore it is necessary to create this energy need while lowering the costs itself. The photovoltaic system is designed with 1.200 PV solar panels on the roof and connected to an inverter system. The energy is sent to the general switching room with appropriate cables and then redistributed in the building. It will be possible to storage the extra energy produced in batteries and reuse in a second moment the energy that is requested by the building systems.
5.18 - Electric System The electrical system will start from the electric meter and from there on to the general switchboard situated in the first ground floor. Every level of the building will have his own switchboard in order to have an easy maintenance management. All switchboards will manage the lighting, single room climate regulation, plugs, emergency lights. In each room are disposed several junction boxes to optimize the distribution to each plug or lighting points.
All cables are designed to fit for the specific use and big enough to support the current without generating heat on the cable itself. In each switchboard there will be suitable breakers in accordance with electrical safety laws. This will also protect the all the equipment’s that are attached to the plugs. The grounding is one for both buildings and it will be in bare copper all around the building itself.
5.19 - Emergency Devices In case of blackout a generator will start working in order to maintain the primary buildings needs on. In this case it will be studied an emergency plan to determine witch are the primary needs and which are secondary needs that can be switched off. In each floor there will be certain number of emergency lights to create a path to the emergency stairs and create a safe way out for the workers.
5.20 - Automation, security and monitoring system The entire buildings will have a self monitoring system that will constantly control the primary needs in terms of electricity, climate comfort and security. As for the first part the automation system will control constantly how much current the building is consuming and how much is coming from the photovoltaic system. This gives a specific type of output in order to understand the annual consumptions of the buildings. As for the climate and comfort automation, the system will allow the users to forget to adjust the climate every time, but will create in automatic the perfect climate conditions in each office. Even in this case the system will give as an output an annual report on the total consumption in terms of electricity dedicated to the climate system. The security system is conceived as a high standard. Closed circuit cameras, servers, recorders and sensors all around the buildings and controlled all from the “security control room” situated in the ground floor of the first building. A security company will be in charge of controlling all the systems and will manage to contact the single maintenance companies or the authorities in case of need. Data from the servers and automation system will be used to evaluate the total consumptions of the “building systems” and generate a general annual report from witch it will be possible to value further improvements of the single systems and create a life cycle of the building with a benefit in terms of annual management costs.
6 -DESIGN INNOVATIONS Innovative solutions in terms of comfort for inhabitants and building smartness are integrated in our design as well as sustainable solutions for minimizing the impact of construction over the site, handle the impact of vehicular traffic, adopt energy savings strategies in order to minimize costs and pollution, storm-water management for lowering the impact of atmospheric precipitations on the building and increase the life cycle of architectural parts and materials and finally create synergies between all these above mentioned features to give GNBC an outstanding modern headquarter with SMART features.
LEED strategies in design include: A| Solar radiation protection on the exposed facades and roof with shading systems and low emitting glass panels for exterior curtain walls in order to minimize consumption of HVAC systems and size.
B| Reduction of heat island effect on roof and on outdoor areas in order to minimize impact of overheating of external surfaces. This strategy is implemented by using vegetation and landscaping, reducing the vehicular infrastructure such as parking areas that are conceived to be under the footprint of the building, which is to say in the basements. This approach is used to kill the heat-island effect due to large asphalt parking area near the building.
C| Use of natural daylight in most of work spaces and rooms in order to maximize visual comfort and reduce use of artificial sources to affect cost reductions. At this scope the lighting plan will be based on two complementary channels, the general lighting of the interior spaces integrated with daylight providing low level of power and specific lights per single workstation unit individually controlled.
D|Indoor air quality is implemented by HVAC and Air Treatment Units for fresh air circulation with zones sensors as stated before.
E|Natural ventilation implemented in the outdoor spaces, by adopting space configurations allowing shading and air movement in order to increase human comfort.
F|Water use reduction strategies are implemented both in the indoor water management for bathrooms and hydric sources and outdoor for potable water reduction in the landscape irrigation. Reuse of rainwater systems are proposed in order to limit usage of potable water and preserve resources.
G|Energy efficiency solutions are implemented to reduce demand, increase performances and reduce environmental impact. Key concepts in the design are high performance facade systems for the building envelope such as low emitting glass and insulated curtain walls, ventilated facades with layering which increase insulation coefficient and lower the request for air conditioning, HVAC control with multi/zones in order to optimize flows and request for air conditioning, use of renewable energy such as photovoltaic systems to lower demand for power supply.
H|Occupants comfort and productivity is guaranteed by thermal comfort control and humidity low levels, acoustic solutions , use of low emitting material and furniture free from chemical pollutants, ensure lighting satisfaction and daylight plus views.
I| Green roof is a strong solution to synergy for energy reduction and climatic control. This is used in the roof garden with both intensive and extensive vegetation.
7 – INTERIOR FURNITURE AND EQUIPMENTS 7.1 Partition Systems The unique glass partitioning system proposed can be integrated into suspended ceilings and floating floors as per our interior design proposal, forming an acoustic barrier that reduces transmission of noise from one room to another by as much as 41 db.
7.2 - Operatives The proposed office solution anticipates the revision of European standard UNI EN – 527/1 that requires a work top height of 74 cm ± 20 and a desk depth of less than 80 cm for use of laptop computers or flat screens smaller than 17”.
We intend to provides the interior spaces no barriers to light coming in from the glass façade and increase views toward the outside in order to increase the internal human comfort for a high performance during working hours. All the employees and teams are supposed to feel they work in a unique and united work environment with no separation between the working units and departments.
7.3 - Operatives Workstations The proposed office solutions anticipates the revision of European standard UNI EN – 527/1 that requires a work top height of 74 cm ± 20 and a desk depth of less than 80 cm for use of laptop computers or flat screens smaller than 17”. The ergonomics of all the equipment and furnitures are a core concept of our design. The chosen set of workstations are conceived for open spaces and wide office areas where employees can easily move around, exchange informations and sit in front of their collegues so that each unit can become a meeting spot for small groups. Proposed chairs are designed for maximum comfort during all tasks for at least 8 hours a day. Punctual lighting is often integrated in the workstation or located right close to it to maximize the lighting power on the working surfaces.
7.4 - Executives The warmth of leather, in classic, natural or modern shades is a must for GNBC executives. The striking look of the 7 cm tops, with 45° edge fits the interior design of the working spaces and makes the executives offices extremely modern and comfortable. Two stylistic features are set into an unique combination of good design and functionality. Cabinets, in black and white match with the desks and chairs. The warmth and natural beauty of wood envelop the proposed desks to create new sensory emotions and aesthetic values, while maintaining all the simplicity and versatility of this range. Light Oak or Walnut veneer completely covers the 5 cm thick tops, giving a perfect handcrafted finish.
7.5 - Seating Meeting is the most widely varying working needs and the proposed seating system combine maximum comfort with a high standard of quality. Equipped with the normal adjustment systems for backrest, seat and armrests, the executive series also allows fine adjustment of the mechanism which provides oscillation and synchronised movement between backrest and seat, with the possibility of locking in several positions and anti-shock release.
The operative workstation arm-chair that we propose is ergonomic, easy to be maintained and the best configuration for Ghana is in our opionion has the tech fabric that reduces the backseat heating.
7.6 - Congress hall seats In regards to the congress hall we suggest a fabric armchair with adjustable backs weightsensitive. This allows the attendant to have a minimum level of flexibility in the position during all the time of the event and this would guarantee extreme comfort.
