EE Ignorance

11 05 2010

A few years ago I was on a marketing visit to a hospital for non-energy related services and of course I had to work energy efficiency into the conversation.  “So, have you done any energy efficiency upgrades in recent years?”  “Yes we replaced windows in the old section of the facility and installed new boilers.  We’re all set with energy efficiency.”

Palm, meet forehead.

I could be a lousy salesman but that conversation ended with a pregnant pause.  This was a hospital, probably the most energy intensive type of commercial facility there is, and replacing windows might reduce consumption by 0.01%.  New boilers could do anything from saving some energy to using more depending on how they are controlled.

One of the major obstacles to capturing real and substantial savings in commercial buildings is overcoming ignorance of how these facilities use energy.  They use energy far differently than homes but Joe in the maintenance department or Sally the executive think the way to 10% savings is new windows, new boilers and more roof insulation.  Good luck with that.

When I talk about energy efficiency in commercial and industrial facilities I talk about controls, systems and processes, NOT pieces of equipment and components.  At the end of the presentation I say all boilers are 80% efficient.  All chillers use 0.6 kW/ton.  All lighting fixtures produce 80 lumens per Watt.  Of course this isn’t literally accurate, but the point is, the building can be operating very poorly as a system, such that plus or minus 20% on these performance metrics is dwarfed by poor operation.  The control programming is awful.  The system could use some additional control points and maybe a few components need to be added.  When added up,  the waste generated by these controls and system operations dwarf the few percentage points for the boiler efficiency or one or two tenths of a kW per ton for the chiller.  See The More You Spend The More You Save.

I was reminded of this once again this week as I read this article on the Empire State Building.  The owner says windows are “a key to efficiency”.  Even including the daylighting controls he is talking about, this won’t amount to a peanut of the 38% energy savings they plan to achieve.

Columbia University research declares green and white roofs in NYC “help prevent energy losses”.   That may be factually incorrect but the more arguable thing is, it has a tiny effect on heat transfer through the roof.  Green roofs include plants which require dirt and moisture to grow.  Moist soil has lousy insulating qualities.  The benefits of a green roof include reduced runoff into rivers, lakes, and oceans, transpiration which reduces temperature on the roof’s surface and thus reduces heat island effect, roof life extension, and possibly energy savings if building cooling system equipment is located on the roof.  A white roof will save some cooling energy but costs you some extra heating energy in winter.  See  our Energy Brief “Cool Roofs in Cold Climates“.  I’m not bashing green and white roofs.  I would use one or both on my building, but for reasons other than energy efficiency.  These other benefits pile up.

We surveyed 150 buildings in NYC about 16 months ago and believe me, there is huge potential in the city but it isn’t going to be realized with windows, boilers, and green and white roofs.  Like the Empire State Building probably was prior to this $20 million retrofit, buildings have 1960s and 1970s technologies and crappy old pneumatic controls.  There are steam-turbine-driven chillers, which have to have horrible efficiency because the steam pressure is so low.  The heat rejection would be massive.  According to my calculations, with a perfectly efficient turbine and an efficient chiller, the cost to operate a steam driven chiller would be twice that of an electric chiller at the same efficiency.  Why?  Because of the relatively very low steam pressure (compared to power plants) the steam-driven chiller uses.  If I were to use real numbers, this could easily balloon to 6x the cost.  E.g., these old chillers are probably half as efficient as a new one- tops, and the turbines won’t be perfect like I assumed.

So what is the solution to widespread ignorance of commercial and industrial facility operation, systems, processes, controls, and how to reduce energy consumption?  Send me an email and I will tell you.  jli@michaelsengineering.com.  It works really well.

written by Jeffrey L. Ihnen, P.E., LEED AP

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