Air and water - different space requirement
In regards to heating and cooling there are two available options – using air or using water. The essential difference between the two, is the fact that water can carry many times more energy than air. This means that the infrastructure for carrying energy by the means of water can be significantly smaller, less bulky, than the otherwise needed for transporting the same amount of energy by air.
However, the ventilation requirements can only be met by using a system for air. Therefore, ductwork for air is always needed but will be smaller in size if it is only for air quality, rather than for both air quality and temperature.
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Combining air and water
The investment cost of a hydronic system is in general higher than the cost for a system for air. Yet, many buildings are built with multiple stories, and if the ductwork in a tall building is minimised thanks to the above choice, levels can be gained. The payback time on the investment is then shortened as more floor space can be sold or rented out.
Another perspective of space and payback, is the volume or “sense of room”. Extra ceiling height can give a spacious and airy impression of a room which is normally seen as attractive, and may allow for increased rent. A hydronic system can allow for aditional ceiling height thanks to its lesser space requirement. On the other hand, there is a wide range of exposed air diffusers which also allow for a more spacious feeling inside.
How to get things right
With the above said, at Swegon we offer products for both air and water, for exposed installations as well as for installations in suspended ceilings. With that, it is possible to meet demands in regards to many criterias, for example space, look and demand.
To easen the design phase and make sure that the selected alternatives meet the set requirements for the indoor climate, we can assist in person or with our Swegon ESBO digital software.
ESBO is a support tool for the entire process, from project planning through to a finished building, which offers a productive and comfortable indoor climate. The software handles factors direclty connected to HVAC as well as to factors tightly linked to the project. Climate conditions, customer demands, energy requirements and legislations are examples of both.
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The balance between shafts and floor space
Space efficiency has been mentioned in relation to air- and waterborne systems and it is also of significant interest in terms of air handling units. It may be assumed that air handlers should be placed in the basement, on a plant level inside the building or on the roof-top. What can be more space efficient is to spread them out on different floors. The exceedingly large shafts for ductwork extending all the way up or down in the building may then be avoided.
At the same time, units may in a decentralised solution be placed in different spots, along different sides of the building or in the middle of a building where no light is coming in. This way, the unit’s purpose, the indoor environment’s characteristics and energy-efficiency requirements may be better met. It is though important to acknowledge the required floor space for fan rooms on a number of levels in a building contra a centralised location for all units. A detailed comparison between the options might be necessary, but well worth the effort.
Good to know, the decentralised solution is too often overlooked despite its benefits of space and flexibility.A decentalised solution allows for parts of a property to be utilised, while minimising energy consumption for ventilation, heating and cooling in parts that are empty.
Capacity affects cost and space
Today’s technology allows for the indoor climate in an office to be demand-controlled, meaning that each room or space in a building is ventilated, heated and cooled only as much as needed. In general, that means that the capacity and size of the indoor climate solution and ductwork can be reduced as it is rarely necessary to ventilate, heat and/or cool an entire property to a maximum level at all times.
Having that said, a physically smaller AHU can allow for more floor space to be sold or rented out, and smaller dimensioned ductwork can allow for more ceiling height, and possibly an increased selling price or rent.