energy conservation

[raiderUM]

Hello all,

At my place of employment we are looking at ways to shed load one day a year during peak seasons. We want to call it a "green day". Obviously peak season will be during the summer months, which works out great for us because campus is a ghost town during this time. Looking at some of the utility bills for last year our peak was August at 8.5 million kwh and our December kwh reading was 4.5 million. After speaking with our HVAC manager I was informed that during the month of December our chillers never turned on. So the difference is roughly 5.5 megawatts on average based on 720 hours.

My question is.... During the peak time when campus is fairly empty would we be able to throttle back on the chillers themselves?

For simplicity reasons I will use our main chiller plant as an example, but we have many chillers throughout campus that we would want to throttle back on. For example: The main chiller plants average kw from June-Sept is 500kw and peak is 700kw. This main plant feeds 4 large buildings. Wouldn't we be able to run the chiller at half this kw and allow the chilled water temp to rise a couple of degrees? OR would this cause for the buildings to get to warm and humid?

My thoughts are that is would save us 1/4 of a megawatt just at this one location. Not to mention we have multiple chillers throughout campus.

I'm looking for your guys thoughts on this. Maybe this is just a pipe dream. Thank you

 

[gar]

130208-1050 EST

When I went to school most classrooms and buildings at school were not air conditioned. If it was hot, then windows were opened. Fresh air was nice.

One school I attended, built in the 1800s, was original heated with a wood stove which is still there, and later by gas. Never was and still is not air-conditioned.

I think your question should be directed at school management, and their specialists in the building designs.

.

 

[Besoeker]

Hello all,

At my place of employment we are looking at ways to shed load one day a year during peak seasons. We want to call it a "green day". Obviously peak season will be during the summer months, which works out great for us because campus is a ghost town during this time. Looking at some of the utility bills for last year our peak was August at 8.5 million kwh and our December kwh reading was 4.5 million. After speaking with our HVAC manager I was informed that during the month of December our chillers never turned on. So the difference is roughly 5.5 megawatts on average based on 720 hours.

My question is.... During the peak time when campus is fairly empty would we be able to throttle back on the chillers themselves?

For simplicity reasons I will use our main chiller plant as an example, but we have many chillers throughout campus that we would want to throttle back on. For example: The main chiller plants average kw from June-Sept is 500kw and peak is 700kw. This main plant feeds 4 large buildings. Wouldn't we be able to run the chiller at half this kw and allow the chilled water temp to rise a couple of degrees? OR would this cause for the buildings to get to warm and humid?

My thoughts are that is would save us 1/4 of a megawatt just at this one location. Not to mention we have multiple chillers throughout campus.

I'm looking for your guys thoughts on this. Maybe this is just a pipe dream. Thank you

Simplistic but can't you just shut off the air con in areas that are not occupied?

 

[Besoeker]

130208-1050 EST

When I went to school most classrooms and buildings at school were not air conditioned. If it was hot, then windows were opened. Fresh air was nice.

Maybe depends on how hot the local weather gets. Air conditioning just wasn't a requirement where I went to school. It would never actually have been a consideration. But where Mrs B lived until I dragged her, kicking and screaming, all the way over to dear old Blighty, life without air con would be pretty uncomfortable.

 

[raiderUM]

Simplistic but can't you just shut off the air con in areas that are not occupied?

I wish it were that easy, but when you are on a campus this size common sense does not come into play. Professors will call on the weekends complaining that they are too cold or hot and expect us to make them comfortable and they are the only one in the building.

We are attempting to participate in Demand Response but we do not have enough load tied into our generators to make much of a difference. The only way I can see us shedding Megawatts is by throttling back the chillers or turning them off all together. Both of these options are going to cause many complaints.

 

[beanland]

Choices

Choices

For one thing, you can raise the thermostat settings in buildings when unoccupied to reduce the chiller load. You might be able to raise the chilled water temperature when load is light to reduce chiller load. You can also pre-cool buildings so that they are cooled at night and then allowed to wram during the day, using the building mass as a way to store the "coolth." You can install ice or chilled water storage to do cooling at night when it is more efficient and then use the cool during the day to reduce consumption. A comprehensive energy audit by a qualified firm is needed because you are looking at possible control changes, the social impacts of changing temperatures, and maybe capital changes to upgrade chillers to more efficient ones.

 

[K8MHZ]

I wish it were that easy, but when you are on a campus this size common sense does not come into play. Professors will call on the weekends complaining that they are too cold or hot and expect us to make them comfortable and they are the only one in the building.

We are attempting to participate in Demand Response but we do not have enough load tied into our generators to make much of a difference. The only way I can see us shedding Megawatts is by throttling back the chillers or turning them off all together. Both of these options are going to cause many complaints.

I have done energy use surveys for people and when they find out that their high electric bills are due to their life style they always prefer their life style over energy savings.

I don't see how turning off chillers for one day will save anything. The energy not used on that day will not offset the energy needed to bring the rooms back to normal after the shut down. In fact, since the chillers are going to have to work harder to get back to temp, temporarily turning them off and then back on may actually take more energy than just leaving them on. Dialing down a degree or two over time is a far better energy saver than a one day shut down.

 

[__dan]

Hello all,

At my place of employment we are looking at ways to shed load one day a year during peak seasons. We want to call it a "green day". Obviously peak season will be during the summer months, which works out great for us because campus is a ghost town during this time. Looking at some of the utility bills for last year our peak was August at 8.5 million kwh and our December kwh reading was 4.5 million. After speaking with our HVAC manager I was informed that during the month of December our chillers never turned on. So the difference is roughly 5.5 megawatts on average based on 720 hours.

My question is.... During the peak time when campus is fairly empty would we be able to throttle back on the chillers themselves?

For simplicity reasons I will use our main chiller plant as an example, but we have many chillers throughout campus that we would want to throttle back on. For example: The main chiller plants average kw from June-Sept is 500kw and peak is 700kw. This main plant feeds 4 large buildings. Wouldn't we be able to run the chiller at half this kw and allow the chilled water temp to rise a couple of degrees? OR would this cause for the buildings to get to warm and humid?

My thoughts are that is would save us 1/4 of a megawatt just at this one location. Not to mention we have multiple chillers throughout campus.

I'm looking for your guys thoughts on this. Maybe this is just a pipe dream. Thank you

If I had one specialty to choose for myself in electrical, it would be walking facilities and making my salary saving money on the electric bill. Typically facilities like yours are ripe for this as the normal concern is usually jungle rules, make it work regardless of cost.

Regarding your inquiry, couple of thoughts:

If you undercool the spaces you will likely still get great dehumidification and the higher temp dry heat can be very comfortable. You may not be able to shut the equipment completely off, but if you can cool at a lower capacity and maintain the unoccupied spaces 75 to 76 deg or more, there's a lot of cash off the electric bill there. That may be easy to implement also as it's similar to a night setback scenario, but you're allowing the space temps to go up while still maintaining cooling and dehumidification. It may be a just change to the existing electronic space temp and equipment controls. Run the cooling coil blower motors at a continuous but lower fan speed (if able) and/or allow the chilled water valves at the cooling coils to open, but not beyond some fixed max opening during setback. Lets say demand calls for 50% open at the CHW valve and max opening during setback is 30%. Cool it and let the space temp creep up during the day and pull back down at night.

Running the chilled water loop at a higher temp is a big number kW or btu wise but there could be issues. Spaces where you have real demand may run warmer and the adjustment itself may be a manual change right on the chiller. If so you would have to manually change and watch the changes daily, and it may be an issue for the chiller manufacturer. I would check with them for their concerns and approval. There are things that happen inside the chiller with the gas and head pressures the chillers may or may not like (this I have no clue). I would think it could be a winner.

Something else that may cost nothing but brainpower and control changes. Look at the chiller's condenser water temperature. Assuming you have cooling towers for condenser water, look at maxing out the towers and running a lower condenser water temp. Some chillers have very good part load and lower condenser water temp performance, some do not. The towers may be able to pull CNDW temp down to 5 or 6 deg above wet bulb outside air temp. In hot weather you will still be maxxed and above setpoint, so no savings, but in mild weather or at night you may be able to pull the CNDW temps down to a lower setpoint, still keeping the chillers happy. Chiller kW should drop a lot or if you have multiple unit running, maybe drop a running unit. The tower controls can be programmed to follow the wet bulb OAT, down to the minimum the chillers will tolerate. Again, consult the chiller manuacturer for this number, the approved operating low limit for condenser water temp. Trading tower fan kW for chiller kW could be a 3 or 4 to 1 gainer.

The green day thing is a good gimmick. My read, get your name on it and push. It does not have to work at all, it only has to work enough to get yourself some pay and promotion (taking a lesson from everything else). One day is a marketing promotion, to keep the clueless hordes busy congratulating themselves. Look at implementing something that makes your pay saving money while you sleep.

 

[jumper]

I wish it were that easy, but when you are on a campus this size common sense does not come into play. Professors will call on the weekends complaining that they are too cold or hot and expect us to make them comfortable and they are the only one in the building.

Man, I know this problem well. Worked at a college for 10 years.

We saved the most money by going completely automated for all large buildings with energy management contracted to a third party.

The eggheads..er professors were simply told that energy consumption had to be reduced or savings would be achieved by removing adjunct faculty from their departments and other budget cuts. They eventually quit whining.