Friday, December 01, 2006

Booboo Bunny, PE

. Friday, December 01, 2006

Most of you know that I am an engineer. Many of you also know that I am a registered professional mechanical engineer. But some of you out there still might not really know what I do. In a nutshell, I design and specify heating, ventilation, and air conditioning (HVAC) systems for buildings. Depending on the size of the project, I'll also design plumbing and fire protection systems.

The company I work for (Forest Animals A/E) is an architectural/engineering firm. It's "one-stop shopping" if you want a building designed. We primarily do K-12 schools, higher education, jails, prisons, courthouses, police stations, and other public office buildings. A county may need to build a new school or jail and will issue an RFP (request for proposal) which is an invitation to solicit bids to design the job. The big wigs put together a scope of work, a fee, and will go on an interview to try and win the job. Assuming we win the job, the following things happen.

Schematic Design Phase
Engineers don't do too much work during schematic design. We determine what type of HVAC system is the best choice (first cost, energy efficiency, etc) and space requirements (where and how big the mechanical rooms need to be) but that's about it. The floor plan is changing too much at this point to do any "real" engineering work. It's during this phase that the architect develops the concept for the building - what it looks like, programming (the types and sizes of spaces, how they are used, and the relative locations of those spaces), and a preliminary cost estimate. There's a lot on interaction with the building owner to determine his requirements.

Design Development Phase
This phase is just what it sounds like - developing the design. At the completion of this phase, we'll have a "rough draft" of the finished product. It then goes to the building owner for his review. Usually, the floor plan is pretty "set" so I can start doing some "real" engineering work. One of the first things I do is determine the maximum heating and cooling load for a building. We have weather data so that our HVAC systems will maintain a certain indoor temperature 99% of the time. We have load calculation software that calculates how much heating and cooling a room needs. It depends on the building construction (the insulation of the walls, roof, and windows, the outside air temperature, the number of people in the space, how active those people are, heat given off by lights and other electronic equipment, and the amount of fresh air being introduced (just to name a few). A lot of that is dictated by code. So room by room by room, we input all of that information into the load calculation software. Once I get my loads, it's time to select equipment. That typically includes boilers, chillers, pumps, and other pieces of equipment you've never heard of. After selecting the equipment, it's time to lay it out and design the ductwork and piping layout.

Construction Documents Phase
This is the phase where we incorporate any comments from the building owner. It's also where we make sure all of the "i"s are dotted and "t"s are crossed. There's a lot of coordination that needs to happen between all of the disciplines. I need to make sure that electrical has powered all of my equipment. I need to make sure all of my ductwork and piping fits above the ceiling and is accessible for maintenance. Even though a majority of the work is done after the design development phase, the construction documents phase takes the longest. The devil is in the details.

Construction Administration and Beyond
The project then goes out "on the street" and we solicit bids from general contractors to build the job. The contractor will submit shop drawings (which is a funny name because they aren't drawings at all) for us to review. Shop drawings are equipment cut sheets describing the model number, accessories, and performance characteristics of the equipment we specify. It is our job to review the shop drawings to make sure they meet our design standards. While the job is being built, we'll answer questions in the field and make sure that the contractor is building the building as we designed it.

So that's just a brief look at what my job is like.



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