+ Interview: Managing Energy in a Historic Office Building

Some Energy stories are close to home. Just before Christmas a posted notice from the Michael Rosenbaum, the building manager of the Textile Building, where our office is located, announced they were replacing all the standard T12 fluorescents with more energy efficient T8 bulbs. It got me thinking about how much energy the typical office building uses, where it goes, and how the amount could be reduced.

First I checked online and found from several sources that lighting consumes 25-35% of the energy in a typical commercial building, and T8 bulbs are 30-40% more energy efficient than T12’s. That sounded good but I didn’t know what it would add up to. Luckily, Michael was easy to find, extremely knowledgeable, and open to answering my questions:

Better Light with Less Energy
You've started a project to replace all the light bulbs with energy saving ones. Can you say anything about how big this energy saving might be?

“Based on our replacement analysis, factoring the entire building we should save approximately 400,000 KWH a year. This also will provide a fuller lighting spectrum which will improve personal skin complexion and less glare in your office.”

Where Does the Energy Go?
Can you give me an idea of what the major energy needs are in a commercial building like the Textile building is?

“HVAC has many energy associated needs from circulating pumps, fan motors, and individual heat pump units. Textile Building has over 200 individual units in its circulating loop system; elevator machines, water supply pumps, data rooms, lighting, and most commonly the thousands of electrical receptacles that are continually utilized.”

Where can Energy Be Saved?
I've heard a lot about residential energy savings (insulation, sealing, etc.); can you tell what the similar issues are in a typical downtown office business?

“VFD (variable speed drives) are a large source for savings in a commercial building on large machines/pumps. The VFD provides electric on demand, (example) you have a 100 amp motor: if the motor needs 40 amps for 5 minutes then needs 100 amps for 5 minutes then 25 amps.... the drive will supply the demand accordingly, rather then a standard setup, where the motor uses up to 100 amps so the motor is always running and is provided 100 amps.

HVAC automated control system is a large source of savings in a commercial building for the HVAC system. Similar to a residential digital thermostat where there are timed programs and set points to control demand and comfort levels during different periods of the day/night, this system controls the entire building from one centralized station. Insulation of pipes saves a lot electric."

Making an Efficient Historical Building
I previously worked in a historic building that was really cold in the winter because of no insulation on the original block walls, and high ceilings; not very efficient! Can you tell me more about how well the Textile Building was upgraded for energy efficiency when it was updated?

“In 1987 when the Textile Building went through a vigorous rehabilitation and remodel, double pane windows were installed to all windows with the exception to the first floor. Since the Textile Building is a National Historical Landmark Building, there are lots of restrictions to construction. Most important is none of the visual aesthetics can be changed, therefore the first floor windows had to say the single pane metal frame prewar style.

The building is a brick building, and there had been upgrades to the interior for insulation as you will notice that visually the walls are not brick from the inside (Although there are tenants that have spent lots of money to remove the energy efficiency layers to re-expose the bricks in their offices for an aesthetics appeal).”

Higher Ceilings = Higher Heat Bills
Are there any other unique energy issues you know about in commercial buildings that you could tell me about?

“A lot of times companies would also remove the drop ceiling grid to enhance the height and aesthetics of their space, which also reduces the energy efficiency of the space by exposing concrete ceilings. Concrete is a conductor, and removing the ceiling increases the amount of area by 20% that needs to be comforted; in particular increasing height and the highest point being concrete, so when heat rises (higher than typical) and then cools quickly (concrete ceiling) making the lower space where people occupy even colder.

Electrical surges are a big issue which tends to fry computers, motors, pumps... they also cause blackouts.”

Well, there’s a quick look at the typical energy issues facing a commercial building owner, quite a lot to consider!