What Is A Green Building (Part 3)

Posted on Sun 03/01/2009 by



In the two earlier posts, I discussed how what is basically an old technology, Combined Heating and Power could be used to provide the electrical needs for large buildings, and in the second post just how large the office buildings sector is in the U.S. and how much of the total overall power mix is consumed by those office buildings.

With this post, I’ll be looking at some specifics and how something like this actually can be a viable option.

Again, I have used the vast database that the Energy Information Administration (EIA) provides for the information, this database providing everything anybody would ever want to know about electricity generation and consumption in the U.S.

As I showed with the chart in the previous post, we can see the disposition of electricity in an average office. The power used just in office buildings across the U.S. amounts to 8.5% of all the available power used, and even though that percentage might seem low, it amounts to all the power produced by 25 large power plants with a nameplate capacity of 2,000 MW or more. Having said that, can we calculate for individual office buildings, and why I say that is that it directly relates back to $5 Billion allocated in ‘Porkulus’ for ‘Green Buildings, so if we could calculate for individual office buildings, we might have a ‘ballpark’ on how many of the Federal Government Office buildings that amount would stretch to.

It is something that can be calculated, the electricity used, the costs for the electricity used, and extrapolated out from the amount of electricity used, we can work out the size of the plant needed, its costs, and end savings if something like this were to implemented.

I have a reason for selecting The Empire State Building, which is quite obviously not a Federal Building. Why I selected this one is that it is the largest office building in the U.S., well second largest really, after the Pentagon, but I’m selecting this one because it is one of those skyscraper office buildings and would be easier for most of you to actually envision, and also to impress upon you the scale of the project. Keep in mind that this is only ballparking, and even though the figures for costs are just that, ballparking, they would be close to the mark.

Empire State is virtually all office space, and has as that floor space two and a quarter million square feet.
The EIA site has figures for power use extrapolated back to an average power use per square foot, and the average is around 19 KiloWattHours (KWH) per square foot, and that is just for office space.
So, from those figures the power used by Empire State amounts to 42.75 Million KWH each year. Working backwards from this, that means to supply that amount of power, then it uses just under 4.9 MW from the grid that supplies New York City, made up from numerous power plants, in the main, coal fired plants. So call that effectively 5 MW of power at any one time needs to be supplied to The Empire State Building.

Trigeneration plants come in numerous sizes ranging from 200 KW and all the way up to 5 MW. For the most effective fitment for a building of this size, it might be best to install two 3 MW plants. They can be fitted in the basement of the building, and wired into the current electrical supply to the building.
The cost of the units themselves is around $2 million, so that’s $4 Million for the plants themselves, but that’s not the end of the costs. The installation itself, the cost for wages of the crew that does the work, and then the ongoing costs of the supply and use of the fuel source for the plants. The driving turbines can run on Natural Gas, but other fuels can also be used, say, Biomethane, or even Biodiesel.
Keep in mind that Natural Gas also emits Carbon Dioxide greenhouse gas, but only at a third the rate as for coal fired power generation. Effectively, removing 5 MW of coal fired power from the grid and replacing it with this 6 MW of Natural Gas power would amount to an overall saving in greenhouse gas emissions.
However, the costs would not stop there. Empire State uses low pressure steam for heating, and even though this steam is one of the things that a Trigeneration plant produces, perhaps a more effective use of the plants would be that the whole heating/ cooling/ air circulation for the building be overhauled and replaced as part of the exercise. Newer airconditioning plants could cover all three of those bases.

Trigeneration uses the fuel to drive the turbine which then drives the generator, the hot exhaust from the turbine heats water to steam to drive a second and smaller power producing generator. The steam is also used for steam heating and also to drive an absorption chiller which provides cooling for the building.
Replacing the whole air supply system would provide air circulation throughout the building, and the reverse cycle conditioner could cool in the Summer, and warm in the Winter.

To offset the costs and see if the whole process is in fact viable, the original cost for supplied electricity needs to be worked out.
For Empire State, the cost for the supplied electricity amounts to 10.24 cents per KWH, the average cost for the Commercial sector for electricity. Compare this to what you pay as a householder in the residential sector where you pay an average of 11.3 cents per KWH (varying from State to State, this just the average) and for the Industrial Sector which pays on average 7 cents per KWH for the power they use.

So, for Empire State, their overall power bill for all the office space in the building amounts to $4.4 Million each year, and yes read that figure again, $4.4 Million.
So now ‘bean counters’ start to crunch the numbers. The savings from one year’s electricity pays for the units outright. The extra costs would be paid for in a further few years. There would be the ongoing costs for the supply of the fuel, maintenance etc, but as you can see, the fitment of something like this could be viewed as an attractive option for buildings to actually implement.

There is also an added benefit. The plant will just work as designed all the time, and the power produced will always be that little bit more than what is required for the building itself. Here’s the attractive bit. That excess power is fed back into the grid for New York. The feed in rate for situations like this has to be made attractive, as an inducement carrot to actually do something like this. That feed in rate can be double or in some cases more even that. So any excess power fed back into the grid now becomes actual income for the building itself, and at night time when nowhere near as much power is being consumed that feed in might be quite considerable indeed.

So, even though this might be just conjecture on a ballpark scale, you can see how an option like this now actually does look viable.

The outlay of $5 Billion in ‘Porkulus’ may seem small now, but keep in mind it is only for Federal Government buildings across the Country. It will go a long way, and considering now it’s a case of having been allocated, then those buildings are effectively getting it all for free.

Now that’s not the end of it. You can’t just sit back, fat dumb and happy, thinking that you’ve done your bit if you work in one of these ‘green’ buildings, because this is an attiudinal thing, and people will need to be educated to change their attitudes to keep those buildings as green as they can actually be.

Just fitting the Trigeneration plant is not the end of it. Refer back to the chart in the previous post.
Savings can be made in each of those pie slice sectors. With the 25% for Air circulation, heating and cooling, then fitment of the new airconditioning plant can be offset by adding insulation to the buildings. This might amount to the traditional roofing insulation in the ceiling spaces, but also a good idea would be to instal film on all the windows similar to what is used on cars for filtering of sunlight. You can still see out, just like looking through sunglasses. However. It lowers the intensity of light coming into the building. Increased sunlight coming in can lead to increased heat, causing strain on the aircon plant, the glass tending to magnify that heat, so this film would lower that effect.

The largest savings can be from that 44% lighting slice of the pie. Lighting in the building needs to be totally rethought. New fluorescent lighting can be used providing higher intensity light for lower power consumption. Lower consumption lighting also generates less heat so the aircon again is using less power.

However what needs to be really looked at is the practice of leaving all the lights burning all the time, something that is done mainly for safety reasons. An effective suggestion here might be that the wiring for all that lighting in those office buildings could be changed as part of the work in the ‘greening’ process for that building. All the lighting could be changed for the newer style lighting, and at the same time the lighting switches could be changed. Instead, the on/off switches could be changed so that in the morning, they could be turned on to provide the required lighting for the workplace. However, at night, the lights could be turned to the off position, now wired so that instead off all the lights being turned off, some would still remain lit, providing that safety aspect for the lit buildings, only nowhere near as bright as they currently are.

The Office equipment slice of that chart can also produce savings, and here is where the education process for the ‘greening’ of the building could come into play. Every office could have a monitor, similar to what you might remember from school days. The monitor’s job is to turn on the lights in the morning and to be the last to leave at night. Their job would be to check that all office equipment is turned off, and that the light switch is rotated from the day to the night position. Something like this should not be the job of someone specifically employed for the job, but on a rotational operation throughout the office, because after all, this is the responsibility for all of us, not just the one person. Each person could also be educated to turn of the equipment at their desk, and not just leave it in the stand by position.

So, a ‘Green’ building is a lot more than just the installation of a different type of electrical power supply. It is a mindset that we all need to understand and then to implement.

What I have suggested here might only be part of the overall process, but the option is a good one, and gives you all an idea of just what it means when someone talks about ‘green’ buildings.

That $5 Billion might sound like a lot of money, but believe me, it will not go very far. Something like this is an idea that should be being looked at on a much larger scope, and not just for Federal Government buildings.

It would be a lot of work and cost a vast amount of money, but if we are to follow this trend, then practical situations that actually work need to be looked at, not crackpot schemes like putting a wind turbine on top of every skyscraper.

Perhaps now you can see just why it is that I have been saying from the outset.
This has nothing to do with the environment. It’s just about the money.