How I approach HVAC design: concept

I learned how to design buildings BEFORE I learned how to design an HVAC system. So my approach is unique in a way, in that I started in this field wanting to design buildings and making good architecture. As the vagaries of a difficult job market, in the late 1970s, shaped my career decisions, I ended up designing automatic temperature controls for a contractor, and then moved on to larger HVAC design and project management.

My first impression of a design:

1. Look and listen with an open mind (I will be the first to admit that I am NOT an expert at this part.)

2. Understand the use of the space first, since that often controls the design, regardless of the exterior conditions or the design of the envelope.

3. K.I.S.S. Keep it simple stupid. In the real world, Murphys law does indeed rule.

4. Design with the end in mind: a sequence of controls, a state diagram, schedule matrices, whatever it takes. (Anything that you can write or diagram is possible at this point, although it does help to walk it through every state that is realistically possible)

5. Do not forget #3

The real objective of any design is to provide the user/occupants and objects a safe, healthy, and comfortable environment. Other needs are: a healthy quality and level of light, comfortable or otherwise ‘correct’ temperatures, air movement/direction, fresh air. In any event, it is important to balance the needs of four stakeholder groups and their specific issues:

· Public (codes and LEED/BREEAM)

· User (comfort, safety, health, ‘delight’, perceived value)

As mechanical engineers, we have a variety of system types to choose from for any given HVAC and lighting problem. There are plenty of books on the subject that describe these. There is plenty of precedence and history in HVAC engineering and it is definitely a mature field. Willis Carrier, the founder of modern air conditioning, did his work 100 years ago.

It is easy to get caught up in the decision process, since there are so many choices. But too many choices can be almost as bad as not enough choices. But simple solutions tend to be better, if not best. The task is to list them, rank them, and pick them.

Noel Susskind, PE LEED AP