Climate control and
energy conservation
in campus buildings.
The campus has a unique set of circumstances that causes our climate control systems to have to be radically different than the typical residential HVAC system that many are used to. A few of these include overall cubic volume, the need for energy savings, and much higher occupancy per square foot in many areas.
One of the most confusing aspects of how we do things is the concept of re-heat. Due to the occupancy per square footage of our buildings we cannot simply recirculate air and rely on leaks in the structure or the occasional door opening to supply fresh air to keep Carbon Dioxide levels low. We must rely on a combination of outside air and mixed air depending on occupancy conditions. We do what seems to be the most confusing and counterproductive thing you can imagine, especially in the summer…. We re-heat.
Each office and classroom, with the exception of the MB auditorium, is fed a constant flow of 55-60 degree Fahrenheit air all year long. The thermostat in the room monitors the temperature just like the one in your home, but when the temperature falls below the set-point it opens a pneumatic valve that supplies hot water to a small coil in the duct-work on the supply air side. This heats the flow of 55-60 degree air to just above the desired room temperature.
We calculate the needed airflow to be able to prevent the valve from over-cycling but yet allow the room to be controlled in extreme conditions. If it is very cold outside then we need enough airflow to warm it in the winter. If a room is on the top level, we need enough airflow to cool it in the summer due to the solar gain, or heat transferred to the structure from the sun onto the roof. The supply air temperature is also calculated for extreme conditions, among other things. The flow of 55-60 degrees Fahrenheit supply air is the average across the industry, and has not changed in decades.
I know, this makes no sense yet…
In the summer we cool air from the outside, then heat it back up to your desired temperature. That seems counter-productive right? The upper floors use very little reheat, the lowest levels certainly DO use reheat. The floors sandwiched use a moderate amount of reheat. Sun hitting one side of a building rather than the other also contributes to solar gain. The supply (outside) air temperature has to take into account the distance from the air handler and be able to be used at its coldest setting to maintain a comfortable temperature in all places.
That is what happens on a room-to-room level.
The rest of the system causes this to make more sense:
We have an air handler with a supply and return fan for each level, or large common space. These air handlers also contain a large cooling coil, a large pre-heat coil, and a humidifier. (Humidifiers in Music Building and Smith Hall) The supply air handlers have a damper to control outside air, the return air handlers have a damper to control exhaust air. Between these two air handlers per space is a damper to mix the supply and return air and is called a mixing damper. The air handlers have monitoring for supply temperature, supply humidity, return temperature, return humidity, return CO2, VOC sensing, and smoke detection.
NOW we have some control! This is where the energy savings comes in to play.
In the summertime, if needed, we can take big “gulps” of outside air in the evening when the temperature falls, this air is oxygen rich and also allows us to “turn” the air in the building, much like your home. By doing this we can then mix air for a large part of the day and reduce the flow through the cooling coils used to drop the supply temperature for the individual spaces. In the winter time we can mix air to average out the temperature to rely less on the preheat coil. In more temperate times we can simply use a combination of outside air and mixing to reduce the use of either coil.
Our building temperature control runs on chilled water and steam which is supplied centrally from campus. We also, of course, use electricity to run the local pumps and air handler motors. Locally we reduce the speed of the fans greatly during evenings and weekends to reduce energy consumption. On a campus level the university buys natural gas and the electricity that it does not generate by the hourly rates to run the water chillers. In the deep night hours the university purchases natural gas and electricity for a reduced rate, this is when the large water tank that you may see driving by the Blue Waters Supercomputer is replenished with chilled water for daytime use. This is basically an enormous thermos that was constructed recently that has given the university a significant cost savings. In the winter the university uses a combination of natural gas and clean-coal at the Abbot Power Plant to generate the steam it uses for heating and to also generate electricity. Coal is also purchased and stored as much as possible, except in the winter months. FYI, the university generates a surprising amount of its own electricity which is a significant cost savings.
More energy Savings…
RETRO-COMMISSIONING: About 5 years ago the Music Building went through retro-commissioning, and Smith Hall retro-commissioning just finished in 2015. Retro-commissioning is when a crew comes in and makes sure that our HVAC and electrical systems are running well and functioning as efficiently as they can. This includes comprehensively checking reheat coils for debris and dirt, cleanings, and most importantly; the study and fine tuning of our building automation systems versus our actual usage. On a campus-wide scale this has produced a very significant energy savings. What is most impressive is that the buildings become more comfortable AND save energy!
AUTOMATION: The buildings are now equipped by automation systems which allow user-level monitoring of all data points, including steam usage and chilled water usage. An assigned user, in this case Chad Wahls, can log in and look at trends. For example, if more than two or three people on a floor calls in a hot or cold room, the system can be called up and the parameters investigated. If a problem is occurring at a local level, we can adjust it. If the problem is occurring at a full systems level, we can call Facilities and Services to report the exact problem and to expedite repairs.
We can also set scheduling for different air handlers. For example, the upper level air handler turns on earlier to accommodate for solar gain, this insulates the rest of the lower levels before they can warm in the summertime. The Music Building, in particular, is a very substantial structure. Once the building is regulated, it tends to stay at one temperature due to the amount of concrete, block, and sand present in its construction. The air temperature may vary, but the structure will often stabilize at one temperature.
What you, as the end user, can do…
I hate to say it, but….. Close your windows.
The system was designed in-place to be a closed loop system. If it is cool outside in the spring or summer but humid, and the users open windows, the return fan will then pull humidity into the building causing the humidity levels to skyrocket. Since we need pay close attention to humidity because of the instruments, then we must de-humidify the air in this circumstance. I order for this to be done, we run the cooling coil much like a residential dehumidifier creating condensate. Then the condensate has to be pumped, and then the air must be pre-heated again to 55-60 degrees. If a user ignores the thermostat setting and the room cools past the set-point, then the reheat in the user’s room will also open. The campus also preaches that buildings that are designed to be closed-loop use a lot of energy with open windows regardless of outside temperature. Opening your windows = wasted energy.
Moderate office temperatures.
Especially when gone. If you are chilly then go ahead and bump the temperature up a couple degrees, conversely when you are warm. Changing the room temperature dramatically, especially with an open door will either have little effect or cause over-cycling by constantly having to move the thermostat. Remember, the building structure wants to stabilize at around 70-72 degrees, regardless of the room air temperature. Unfortunately, fighting the thermal properties of this much concrete is futile. Keep your office door closed if altering from 70-72 degrees, and avoid substantial temperature changes.
Common sense says to shut off lights, and it works.
The music building lighting in offices and the smaller classrooms produces very little heat, but it adds up. During retro-commissioning of Smith Hall it was noted that the users ran all of the lights in the Recital Hall all day, and sometimes, all night. Not only does stage lighting use an incredible amount of electricity but it also produces an incredible amount of heat. Lighting is the proverbial “double edged sword.” The numbers taken in the recital hall when doing some experiments with the lighting, even for a few hours, were simply staggering. Not in use, turn of the juice!
Be vigilant.
If a user notices that a space cannot be heated or cooled effectively then please report it to the facilities crew. We likely have no idea that the user is having issues and only a handful of spaces can be monitored on an individual basis. Please note that the reheat system is designed to fail open, and if the user’s room is hot it is because the reheat is stuck open. In the summer time we valve off the reheat coil and it will drive the room air temp low. We are not “wasting air conditioning,” we are just not reheating air.
The real trick comes in the winter when heating is needed but not ALL of the heat. At this point we will try to position he valve so that just enough hot water gets through to keep the user comfortable, however we are still not wasting energy. This takes a bit of trial and error. It’s usually just a short time until a pipefitter can come out to replace the pneumatic valve. Of course, things always fail when it is least comfortable outside.
One of the most confusing aspects of how we do things is the concept of re-heat. Due to the occupancy per square footage of our buildings we cannot simply recirculate air and rely on leaks in the structure or the occasional door opening to supply fresh air to keep Carbon Dioxide levels low. We must rely on a combination of outside air and mixed air depending on occupancy conditions. We do what seems to be the most confusing and counterproductive thing you can imagine, especially in the summer…. We re-heat.
Each office and classroom, with the exception of the MB auditorium, is fed a constant flow of 55-60 degree Fahrenheit air all year long. The thermostat in the room monitors the temperature just like the one in your home, but when the temperature falls below the set-point it opens a pneumatic valve that supplies hot water to a small coil in the duct-work on the supply air side. This heats the flow of 55-60 degree air to just above the desired room temperature.
We calculate the needed airflow to be able to prevent the valve from over-cycling but yet allow the room to be controlled in extreme conditions. If it is very cold outside then we need enough airflow to warm it in the winter. If a room is on the top level, we need enough airflow to cool it in the summer due to the solar gain, or heat transferred to the structure from the sun onto the roof. The supply air temperature is also calculated for extreme conditions, among other things. The flow of 55-60 degrees Fahrenheit supply air is the average across the industry, and has not changed in decades.
I know, this makes no sense yet…
In the summer we cool air from the outside, then heat it back up to your desired temperature. That seems counter-productive right? The upper floors use very little reheat, the lowest levels certainly DO use reheat. The floors sandwiched use a moderate amount of reheat. Sun hitting one side of a building rather than the other also contributes to solar gain. The supply (outside) air temperature has to take into account the distance from the air handler and be able to be used at its coldest setting to maintain a comfortable temperature in all places.
That is what happens on a room-to-room level.
The rest of the system causes this to make more sense:
We have an air handler with a supply and return fan for each level, or large common space. These air handlers also contain a large cooling coil, a large pre-heat coil, and a humidifier. (Humidifiers in Music Building and Smith Hall) The supply air handlers have a damper to control outside air, the return air handlers have a damper to control exhaust air. Between these two air handlers per space is a damper to mix the supply and return air and is called a mixing damper. The air handlers have monitoring for supply temperature, supply humidity, return temperature, return humidity, return CO2, VOC sensing, and smoke detection.
NOW we have some control! This is where the energy savings comes in to play.
In the summertime, if needed, we can take big “gulps” of outside air in the evening when the temperature falls, this air is oxygen rich and also allows us to “turn” the air in the building, much like your home. By doing this we can then mix air for a large part of the day and reduce the flow through the cooling coils used to drop the supply temperature for the individual spaces. In the winter time we can mix air to average out the temperature to rely less on the preheat coil. In more temperate times we can simply use a combination of outside air and mixing to reduce the use of either coil.
Our building temperature control runs on chilled water and steam which is supplied centrally from campus. We also, of course, use electricity to run the local pumps and air handler motors. Locally we reduce the speed of the fans greatly during evenings and weekends to reduce energy consumption. On a campus level the university buys natural gas and the electricity that it does not generate by the hourly rates to run the water chillers. In the deep night hours the university purchases natural gas and electricity for a reduced rate, this is when the large water tank that you may see driving by the Blue Waters Supercomputer is replenished with chilled water for daytime use. This is basically an enormous thermos that was constructed recently that has given the university a significant cost savings. In the winter the university uses a combination of natural gas and clean-coal at the Abbot Power Plant to generate the steam it uses for heating and to also generate electricity. Coal is also purchased and stored as much as possible, except in the winter months. FYI, the university generates a surprising amount of its own electricity which is a significant cost savings.
More energy Savings…
RETRO-COMMISSIONING: About 5 years ago the Music Building went through retro-commissioning, and Smith Hall retro-commissioning just finished in 2015. Retro-commissioning is when a crew comes in and makes sure that our HVAC and electrical systems are running well and functioning as efficiently as they can. This includes comprehensively checking reheat coils for debris and dirt, cleanings, and most importantly; the study and fine tuning of our building automation systems versus our actual usage. On a campus-wide scale this has produced a very significant energy savings. What is most impressive is that the buildings become more comfortable AND save energy!
AUTOMATION: The buildings are now equipped by automation systems which allow user-level monitoring of all data points, including steam usage and chilled water usage. An assigned user, in this case Chad Wahls, can log in and look at trends. For example, if more than two or three people on a floor calls in a hot or cold room, the system can be called up and the parameters investigated. If a problem is occurring at a local level, we can adjust it. If the problem is occurring at a full systems level, we can call Facilities and Services to report the exact problem and to expedite repairs.
We can also set scheduling for different air handlers. For example, the upper level air handler turns on earlier to accommodate for solar gain, this insulates the rest of the lower levels before they can warm in the summertime. The Music Building, in particular, is a very substantial structure. Once the building is regulated, it tends to stay at one temperature due to the amount of concrete, block, and sand present in its construction. The air temperature may vary, but the structure will often stabilize at one temperature.
What you, as the end user, can do…
I hate to say it, but….. Close your windows.
The system was designed in-place to be a closed loop system. If it is cool outside in the spring or summer but humid, and the users open windows, the return fan will then pull humidity into the building causing the humidity levels to skyrocket. Since we need pay close attention to humidity because of the instruments, then we must de-humidify the air in this circumstance. I order for this to be done, we run the cooling coil much like a residential dehumidifier creating condensate. Then the condensate has to be pumped, and then the air must be pre-heated again to 55-60 degrees. If a user ignores the thermostat setting and the room cools past the set-point, then the reheat in the user’s room will also open. The campus also preaches that buildings that are designed to be closed-loop use a lot of energy with open windows regardless of outside temperature. Opening your windows = wasted energy.
Moderate office temperatures.
Especially when gone. If you are chilly then go ahead and bump the temperature up a couple degrees, conversely when you are warm. Changing the room temperature dramatically, especially with an open door will either have little effect or cause over-cycling by constantly having to move the thermostat. Remember, the building structure wants to stabilize at around 70-72 degrees, regardless of the room air temperature. Unfortunately, fighting the thermal properties of this much concrete is futile. Keep your office door closed if altering from 70-72 degrees, and avoid substantial temperature changes.
Common sense says to shut off lights, and it works.
The music building lighting in offices and the smaller classrooms produces very little heat, but it adds up. During retro-commissioning of Smith Hall it was noted that the users ran all of the lights in the Recital Hall all day, and sometimes, all night. Not only does stage lighting use an incredible amount of electricity but it also produces an incredible amount of heat. Lighting is the proverbial “double edged sword.” The numbers taken in the recital hall when doing some experiments with the lighting, even for a few hours, were simply staggering. Not in use, turn of the juice!
Be vigilant.
If a user notices that a space cannot be heated or cooled effectively then please report it to the facilities crew. We likely have no idea that the user is having issues and only a handful of spaces can be monitored on an individual basis. Please note that the reheat system is designed to fail open, and if the user’s room is hot it is because the reheat is stuck open. In the summer time we valve off the reheat coil and it will drive the room air temp low. We are not “wasting air conditioning,” we are just not reheating air.
The real trick comes in the winter when heating is needed but not ALL of the heat. At this point we will try to position he valve so that just enough hot water gets through to keep the user comfortable, however we are still not wasting energy. This takes a bit of trial and error. It’s usually just a short time until a pipefitter can come out to replace the pneumatic valve. Of course, things always fail when it is least comfortable outside.
