The Third Step of the Energy Pyramid
The third step of the Energy Pyramid, Demand Management! This step continues to be one of the hottest topics in building performance discussions and the energy industry because we are going to talk about controls.
As technology advances and data becomes more prevalent, areas of improvement become more clear. This leads engineers to further improve upon performance. I’d like to repeat myself, because the way I said this sentence was purposeful, “areas of improvement become more clear”.
I said this because there may not be any known issues with a building; however, with the use of controls and collecting data, an engineer can learn more information to improve performance even further.
Buildings Need to Eat Healthy Too
Let’s use an analogy because analogies are great. It is like an instagram filter. A lot of those filters just blur the skin, but if you zoom in and make the picture more clear you’ll find the imperfections, dark circles, and zits. Adding controls allows you to see the reality of the image. Well alright, that doesn’t sound that appealing initially, but you need to ask yourself, how you can make this better? Well, if you eat healthier, exercise, get more sleep, and believe you are beautiful inside and out and not care about what others think, suddenly a filter doesn’t feel as necessary.
For a building, an engineer is helping the building eat healthier, exercise, get more sleep, and what is beautiful is that most times it is using less carbon emissions to get there!
I thought this would be a funny analogy but I guess we got a little deep. Demand Management and life advise, you’re welcome!
This is the general idea behind building controls, building automation systems, energy management systems, and demand management systems, all of which do similar things but may work with different systems or have a different focus.
Before we dive in, check to see if you missed anything! I included some helpful links to give you some background.
Let’s backup a second to discuss why this step is the third step in the Energy Pyramid.
If you need even further background, check out the first link below to learn what is Demand. The second and third links go over the first and second levels of the Energy Pyramid. Finally, the fourth links will explain where in the Carbon Life Cycle the Energy Pyramid targets.
II. Energy Pyramid: Introduction & Conservation
Why is Demand Management Third?
At this point in the process, the building is insulated, the equipment is new or well maintained, and performing at it’s best efficiency. The next step is to determine the best methods to control and run the equipment, by managing the load demand. If this step was done first, or second, some steps may need to be repeated. If new equipment was replaced or insulation was added after controls were installed, the energy use may be different and controls would need to be readjusted to the new performance level of the building. Which makes this a clear third place for demand management.
Is this not clear? Ask me a question.
How to Manage Energy
So, what does this step include? Collecting data or adding controls and sensors to collect data.
I know the Controls Engineer is rolling his/her eyes at my oversimplification, so let’s dive in. Man, so much diving today…
An Energy Engineer would begin by collecting utility data.
15 minute interval data is optimal. It is small enough where you have insight into the building’s usage, but not too small to break your computer or get overloaded with numbers. The Energy Engineer will then analyze the data, determine consumption amounts, demand amounts, what is the highest power point, lowest power point, compare seasons and day types, compare to the occupancy schedule, compare to the utility rate, and determine charges and costs as well.
There is a lot to look at with the building consumption data. If this is a full analysis being done by the Energy Engineer, a digital twin may also be created using a special software. The digital twin of the building is created based on current construction, equipment, and usage to simulate the building’s current performance. A simulated building along with the actual consumption data helps the engineer determine where to make the most impactful improvements in the building.
What are some controls that may be recommended?
o. Lighting Occupancy Controls – these sensors determine when there are people in the space. If no people are detected than the lights will automatically turn off.
o. Lighting Dimmers – by allowing occupants to dim the lights, energy is saved because full capacity isn’t necessarily required all of the time.
o. Scheduling – for many different types of equipment a schedule can be set for when it should turn on and off, lighting, HVAC, computers, etc.
o. VFD – A Variable Frequency Drive is a device that is added to a motor on a fan or pump that adjusts frequency and power to control the speed. Often times a fan or pump has only 2 or 3 settings (on & off, or low-med-high), by adding a VFD a system can be fine tuned to the required speed to meet space requirements, making for a more comfortable space and energy savings.
A VFD has some other names as well: ‘AFDs’ (adjustable-frequency drives), ‘ASDs’ (adjustable-speed drives), ‘VSDs’ (variable-speed drives).
o. Economizer – an economizer is part of the air side part of an HVAC system. It is basically a large damper that brings in outside air to cool the space. Typically, there is a temperature sensors on the economizer measuring the outside air temperature. The system will then determine if outside air can be used to cool the space, instead of running the compressor on the HVAC unit.
o. Energy Valves, Pressure Sensors, Air Flow Sensors, and other valves – by utilizing other sensors and controls in pipes and air ducts to measure pressure, flow, and temperature further data can be collected to optimize the system. The amount, type, and location of the sensors will depend on the system type.
Depending on the type of building and HVAC system that is in place will determine what controls are best suited for optimization and energy efficiency. This list just contains some of the major players in the control space; however, there is a rapidly growing amount of companies that make all kinds of sensors to control different aspects of the building equipment. An Energy Engineer on your project can assist with determining where the most savings can be achieved.
Demand Strategies
Beyond adding the controls hardware to your building, a Controls Engineer, Mechanical Engineer, and Energy Engineer walk into a bar to discuss the strategy on how to manage the buildings load.
This includes looking at the designated utility rate and tariffs, occupancy schedule, if there is renewable energy generation, or plans to be, and if there are any current demand issues, like a spike when everyone enters the building. The goal of an energy management strategy is to remove sharp rises in power demand and reduce energy use during high utility price times while maintaining comfort.
Utility Demand Response Program
You may have heard of a Demand Response Program being promoted by your utility company. What is this? Is it related? Is it beneficial?
The reason energy prices are worth different amounts during the day is because the utility’s power plant experiences different energy demands during those times. A lot of utility companies are shifting their peak tariffs from midday 12pm-6pm to 4pm-9pm. This is due to the Duck Curve, something I will write about in another post. For now to simplify things, 4pm-9pm is the time people come home from work and when the sun is going down, meaning we are using a lot more energy and using the most utility power because our solar panels aren’t generating enough. If you are on a Demand Response Program the utility company may contact you when they are experiencing high demand requesting that you reduce your load.
Typically, there are some monetary rewards for participating. It is really up to you and your schedule if you could participate in something like that. Hot summer midday’s and 4pm-9pm are typically when the grid experiences the highest demand.
That’s all for today! Next up, renewable energy, FINALLY!
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