Today, one of the significant objectives in MEP engineering design for HVAC design engineers is to improve energy efficiency, maintain air quality and thermal comfort. Energy efficiency, air quality and comfort in a building depend on how heating, cooling and air distribution systems are designed and this is where careful ductwork design plays a significant role. Ductwork and HVAC system design are important as it ensures indoor air quality, thermal comfort and ventilation. If the HVAC system and ducts are not designed accurately, it could lead to poor air quality, heat loss and make the conditioned space in the building uncomfortable.
The primary function of the ductwork design system is to ensure a least obtrusive channel is provided through which cool and warm air can travel. When designed accurately, affordable packaging designer HVAC air distribution systems will play an important role in countering heat energy losses, maintaining indoor air quality (IAQ) and providing thermal comfort.
To understand how ductwork can be designed in a cost-effective and efficient manner, this article decodes ductwork design and provides a brief outline of the design process, methods and standards.
What is Ductwork?
The basic principle of ductwork design is to heat, cool or ventilate a building in the most efficient and cost-effective way. The primary function of ductwork is to design conduits or passages that allow air flow to provide heating, cooling, ventilation and air conditioning (HVAC).
In the duct design process, the basics of air flow must be understood. Return air goes into an air handler unit (AHU), through a filter and into the blower and with pressure it goes through the A coil or heat exchanger and then it goes out into the supply air system. If the ductwork is designed correctly it enables the AHU to produce the right amount of air through the heat exchanger. In a typical air distribution system, ducts must accommodate supply, return and exhaust air flow. Supply ducts provide air required for air conditioning and ventilation, return ducts provide regulated air to maintain IAQ and temperature and exhaust air flow systems provide ventilation.
For ductwork design to be efficient, MEP engineering design teams need to have designers with a mechanical and engineering background. Ductwork design specialists or building service engineers must also possess thorough knowledge of other disciplines such as architectural, civil and structural concepts to ensure HVAC systems are clash free.
The Ductwork Design Process
The ducting system design process is simple, provided that the specifications are clearly mentioned and the inputs regarding application, activity, building orientation and building material are provided. Based on the information provided calculations can be completed to create an energy-efficient and clash-free design. Typically, air conditioning and distribution systems are designed to fulfil three main requirements such as:
• It should deliver air flow at specific rates and velocity to stipulated locations.
• It should be energy efficient and cost effective.
• It should provide comfort and not generate disturbance or objectionable noise.
The process of ductwork design starts once architectural layouts and interior design plans are provided by the client or MEP consultants. Building service engineers then require specification requirements such as application, the number of people, the orientation of the building and architectural characteristics to make calculations on heat load and air flow. Before any calculations are carried out, single line drawings are drafted to showcase the flow of ductwork in the building. Once they are approved, calculations for heat load and air flow are conducted. Once the heat load calculations are complete, the air flow rates that are required are known and the air outlets are fixed. With the calculations, specifications and layout, the ducting system design layout is then designed taking into consideration architectural and structural details of the conditioned space and clashes with other building services such as electrical, plumbing (hydraulic) and mechanical services.
To start the ductwork design process there are inputs required regarding details about the type of application, specification requirements, building orientation, architectural characteristic and material.
• Application type – Ductwork design will vary based on the type of application the building will be used for such as manufacturing, data centres, medical applications, scientific research and comfort applications such as restaurants, offices, residences, institutional building such as schools and universities.
• Specification requirement – To create an efficient duct design, designers need to know what type of activity will be conducted and the average number of people that will use the conditioned space. This will help in calculating the air flow, velocity and heat load required to maintain temperatures and IAQ. In comfort applications, for instance, an office or restaurant will require different duct design and air velocity than a residence.