Pramod Kumar Jha will be speaking at HVAC R Expo this November. He shared with us some insight on HVAC systems for infrastructure projects. Pramod is the Senior Mechanical Engineer at Atkins, member of the SNC-Lavalin Group and his topic at the HVAC R Talks is "Design of environmental control and ventilation systems for metro projects in middle east region."
How do metro systems differ from regular buildings in terms of their HVAC systems?
In the regular building projects (for example, hotels, residence, office complexes projects), normally buildings are identical and have typical floors and typical design solutions that could be adopted. In a metro project, the buildings (e.g. stations, depot/s, operation control centres, tunnels, operation control centres, viaduct, tunnel ventilation shafts, emergency egress points, etc.,) have different, shapes, sizes and interconnected with each other operation wise. This means, an issue in any of the buildings will also have an impact on the trains operation and the operation of other interconnected buildings which is not the case for regular project buildings. The HVAC engineers need to study and provide customised design solutions to specific buildings. Sometimes, HVAC equipment also needs to be customised to satisfy the requirement coordinating with the manufacturers.
The metro buildings accommodate special (rail power, platform screen door control, automated fare collection, tunnel ventilation systems and communication) systems in addition to the systems of the regular buildings. Therefore, specific HVAC systems with redundancy provisions are required to ensure the trouble-free train operation.
Being the part of infrastructure projects the HVAC system is to be designed for anticipated future modifications/replacement of equipment/ease of maintenance/enhancement etc.
In a public transport system, buildings in the metro projects need to follow stringent reliability, availability, maintainability and safety (RAMS) requirements as per international requirement. This means, for functional requirement, new equipment, space allowances and robust but simple HVAC systems must be easily and quickly be maintained.
Coordination with more stakeholders for design inputs are required in comparison to regular building projects. Due to the large quantity of cooling and ventilation requirements, HVAC equipment are very big, therefore noise and vibration control measures become an issue and the HVAC system designs have solutions for the same.
What particular challenges does this present for engineers and how are they overcome?
Most of the metro projects are developed to resolve the slow passenger movement, traffic problems and environment challenges (pollution) in cities with congested areas, therefore the geometry and challenges of individual station and other buildings are different. The HVAC engineers face many challenges while designing the HVAC systems for metro projects. Some of the major challenges are:
1. The building changes based on geometry, levels, number of passengers travelling form a station to another station and nearby buildings availability. For example, based on locations, the metro stations could have different numbers of entrances, levels, could be underground, at grade or above ground. The engineers overcome all these challenges by clearly understanding the requirement of all the stakeholders/design team leads (architecture, structural, geotechnical, rail system, contractor, codes, authorities, etc.) and provide their inputs to architecture and structural teams at an early stage of the project to provide a HVAC system that is fit for purpose. The HVAC system design schemes are to be standardised as far as possible. However, for some cases the design solution should be customised to suit the specific requirement, if need be.
2. Large capacities of equipment and system sizes: Due to the extreme weather conditions in the Middle East, the equipment sizes are big, for example the tunnel ventilation fans could be as large as 3200mm diameter and duct could be 5000 mmx 3000 mm. Similarly, the air handling units and other equipment would also be bigger, it means proper installation detail, plant space, delivery route, maintenance space and other strategies are to be considered from concept design stage.
3. Latest software including HAP, IES, Building Information modeling (BIM), Computational Fluid dynamics (CFD), Subway environment simulation (SES) to be used for station HVAC and tunnel ventilation system sizing.
4. Normally metro projects are a design and build projects, where stakeholders are in different design phases of their systems and the level of their design input may also vary and likely to be changed. Therefore, HVAC engineers need to have sufficient space proofing for the MEP plant rooms to avoid big changes. Engineers to use previous project space planning as guidance for space proofing and maintain a design risk register documenting the risks and solution agreed with stakeholders at each design stage.
Does the Middle East climate present any particular challenges in this regard?
The Middle East climate being very hot, humid, dusty and corrosive imposes many challenges to engineers. The cooling requirement per square meter area are much higher in the Middle East than any other parts of the world. Normally tunnels cannot be cooled by train push pull effect to ambient air and require cooling by chilled water system unlike other countries (with low ambient temperature) where tunnels are cooled by outside cold fresh air by train push-pull effect. Hot and humid climatic conditions increase the cooling demand and as a result large cooled air supplied to the space. Which result in the requirement of large plant rooms, delivery routes, larger duct sizes, more power consumption, generate large noise and services coordination is a challenge. Due to high ambient temperature HVAC equipment are de-rated and work on much lower efficiencies. This means more power is consumed and equipment's service life is reduced. The dust and high wind impose further challenges of large sand trap louvres and maintain positive pressure inside the buildings.
What projects are you currently working on?
1. Riyadh metro (KSA) Package -3 (Lead Mechanical Engineer/Technical Authority).
2. Bluewaters Development, Dubai Building services Design Lead
What benefits do you see in participating at the HVAC-R Talks?
It is a matter of pride for all Middle East HVAC engineers that this year The Big 5 event theme is after HVAC-R. Participating in this event for the HVAC -Talks and sharing our knowledge and experiences on HVAC system design for metro projects will not only help HVAC sector engineers but also to the other discipline practitioners including architects, structural, Interior designers, etc. to know the challenges faced by HVAC engineers and take a collective approach in design. It will be great to interact with like-minded people from the globe and share & learn from them. This knowledge sharing would be giving back to the HVAC engineers society and benefit hearing from them. As it will be an interactive season and exchange of knowledge would be the key outcome.
About Pramod Kumar Jha -
Pramod is a Chartered Mechanical Engineer registered with the Engineering Council, UK and the Institute of Engineers, India. He is also MBA in Project Management and registered as a certified Project Management Professional (PMP)® with the Project Management Institute, USA. He has an in-depth knowledge with 12 years in Middle East and overall more than 22 years of experience in Building Services design, installations, testing & commissioning for various types and sizes of projects, including Metro, Airports, District cooling plants, Data Centers, Mixed-use commercial developments, Power plants, Cleanrooms, Hospitals and Offshore Oil & Gas. He has a proven track record of efficient design deliveries, team leadership, managing multicultural global design teams working at various positions in project life cycle. Delhi Metro, Dubai Metro, Makkah Metro, Kolkata Metro, Riyadh Metro, GRT Bluewaters Development (Dubai), King Abdulaziz International Airport (Jeddah), Central Market Redevelopment (Abu Dhabi), Opera House (Dubai) are the projects he has been involved with to name a few.
You can hear more from Pramod on "Design of environmental control and ventilation systems for metro projects in middle east region." at the HVAC R Talks on 27th November, 13:00 - 13:45.