Working of Off-peak Cooling Systems

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Air conditioners consume a lot of energy, so if you want to adopt an eco-friendly approach, opt for off-peak cooling.
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Green energy is a major topic of discussion now, and there are various ways to generate and manage energy more efficiently. Off-peak cooling systems are an innovative way to utilize energy wisely. These systems use energy during the night when the demand is low. Air conditioning consumes a lot of energy, and by using some of the electricity required to cool the air at night, it reduces the burden on the energy grid during the peak demand hours of the day.

By doing so, the demand for electricity is redistributed, which helps in avoiding brownouts and blackouts. It also takes advantage of lower electricity rates during off-peak hours. Off-peak cooling systems have other advantages as well. Traditional air conditioners consume more energy as they get hotter, and the more energy they consume, the less efficiently they use it. Off-peak cooling systems not only shift the demand for power to a different time of day but also create a more stable cooling environment that can provide the same cooling capacity by consuming less energy.

Utility companies need to meet the energy demand during peak periods in any way possible. They bring less efficient and dirtier plants online if required and purchase energy from other power plants on the grid at premium prices, passing those charges to their customers. They also expand their facilities when they cannot meet current or projected demand. By making the energy grid more efficient by distributing the demand for electricity and reducing energy consumption by running air conditioning at optimal performance, greenhouse gas emissions can be decreased, and the need for more energy plants can be postponed. This is good news for the environment and helps keep the cost of energy under control [source: Katz].

In the next section, we will discuss how off-peak cooling systems can work at night and still cool the air during the hottest part of the day.

Off-peak Cooling Fundamentals

Off-peak cooling systems use electricity to freeze water in special insulated tanks that contain refrigerant-filled coils. These coils circulate ethylene or propylene glycol and a water mixture that is super chilled to well below freezing. Once the water freezes, during the night when energy demand is low, it is ready to be used to cool the air the next day. This process is called charging, and a charged off-peak cooling system requires very little energy to remain cold in standby mode until it is ready to be used to cool the air in a home or office building.

As the building starts to warm up during the day, the air conditioning turns on, and the chilled refrigerant from the off-peak cooling system keeps the building’s air cool. The glycol cycles through the ice-filled tanks periodically to cool back down after being exposed to the hot air, and eventually, this exchange of hot for cold melts the ice. In the evening, the system charges again, freezing the melted ice with a chiller and preparing the system for the next hot day.

The article discusses the use of off-peak cooling systems, which take advantage of lower energy costs during non-peak hours. While some systems use other refrigerants or different design strategies, off-peak storage is the most common for large buildings. However, smaller and more cost-effective systems are being developed for residential use. The savings from off-peak cooling come from lower energy costs, but this advantage may disappear if energy rate structures change. The article also explores different off-peak cooling systems, such as the Ice Bear 50 and the ICE-BANK model 1045 C tank, which are suitable for light commercial and residential use.

The origin of air conditioning can be traced back to 1902 when Willis Carrier invented a system to remove humidity and reduce heat at a printing plant. This invention led to the birth of the air conditioner. The first home air conditioner, known as the Weathermaker, was introduced in 1928.

Off-peak cooling has a promising future as power companies offer incentives for using power during off-peak hours. There are also disincentives for businesses that use power during peak times, such as time-of-use tariffs and demand charges. Many power companies offer time-of-use pricing for residential customers. The R22 coolant used in current air-conditioning systems will be phased out in favor of the more eco-friendly R410A. This may require a costly conversion, which could be a good time to consider off-peak alternatives.

Richard Bourn developed the Night Sky project, which uses a roof-mounted system to cool buildings during the hottest part of the day. The system sprays water, which is cooled by the night air. The project has shown a reduction in peak cooling demand and is projected to double a roof’s effective life. These creative energy conservation techniques are changing the way we think about our power needs.

Additional Information

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Sources

  • ACU Air. “Tips for Picking an Air Conditioner.” No date. March 28, 2009. http://www.flex.net/~lonestar/buyac.htm
  • Building Green. “Off-Peak Thermal Energy Storage Cooling Systems.” No date. March 25, 2009. http://www.buildinggreen.com/auth/productsByCsiSection.cfm?SubBuilderCategoryID=3804
  • Calmac. “Education – What is Off-Peak Cooling (OPC)?” No date. March 24, 2009. http://www.calmac.com/education/
  • Calmac. “Icebank Ice Storage Systems.” No date. March 25, 2009. http://www.calmac.com/downloads/ICEBANK%20Ice%20Storage%20Systems.pdf
  • Checket-Hanks Barb. “Residential Thermal Energy Storage.” August 5, 2005. March 25, 2009. http://www.achrnews.com/Articles/Feature_Article/3fef95067a06a010VgnVCM100000f932a8c0____
  • Chvala, W. D. “Technology Potential of Thermal Energy Storage (TES) Systems in Federal Facilities.” July 2001. March 30, 2009. http://eere.pnl.gov/femp/publications/TES_MktAsmt-13489.pdf
  • Department of Energy. “Nightsky – A New Roofing Technology.” No date. March 23, 2009. http://www1.eere.energy.gov/inventions/pdfs/integratedcom.pdf
  • Du Bois, Denis. “Ice Energy’s “Ice Bear” Keeps Off-Peak Kilowatts in Cold Storage to Reduce HVAC’s Peak Power Costs.” January 16, 2007. March 30, 2009. http://energypriorities.com/entries/2007/01/ice_energy_peak_power.php
  • ED+C. “Web Exclusive! Hewlett Foundation Building Uses Off-Peak Cooling.” July 1, 2004. March 28, 2009. http://www.edcmag.com/Articles/Feature_Article/8f57bb13fb697010VgnVCM100000f932a8c0____
  • Hauer, Andreas. “Innovative Thermal Energy Storage Systems for Residential Use.” No date. March 24, 2009. http://mail.mtprog.com/CD_Layout/Poster_Session/ID188_Hauer_final.pdf
  • Hindustan Times. “Off-peak Cooling for Greenspaces.” February 18, 2008. March 30, 2009. http://www.pbcnet.com/html/newsclippings/180208_HT.html
  • Ice Energy. “Ice Bear – How it Works.” No date. March 25, 2009. http://www.ice-energy.com/products/howitworks/tabid/163/Default.aspx
  • ICT. “The coolest thing in air conditioning today – ICE.” No date. March 28, 2009. http://www.offpeakcooling.ca/Thermal%20Energy%20Storage%20TES%20Ice%20Ball%20brochure.pdf
  • Innovative Cooling Technologies. “Off-peak Cooling.” No date. March 24, 2009. http://www.ictcanadaltd.com/OPC%20TES%20Primer.pdf
  • Katz, Gregory H. “Green Building Costs and Financial Benefits.” 2003. March 28, 2009. http://www.cap-e.com/ewebeditpro/items/O59F3481.pdf
  • LaMonica, Martin. ” Ice-powered Air-Conditioner Could Cut Costs.” August 1, 2006. March 30, 2009. http://news.cnet.com/Ice-powered-air-conditioner-could-cut-costs/2100-1008_3-6101045.html
  • MacCracken, Mark M. “Thermal Energy and Peak Load Reduction.” July 16, 2007. February 26, 2009. http://www.authorstream.com/Presentation/Savina-26103-Off-Peak-Cooling-Thermal-Energy-Storage-Load-Reduction-Benefits-Natural-common-TE-as-Entertainment-ppt-powerpoint/
  • McIntire-Strasburg, Jeff “Night Wind” Project to Test Electricity Storage in Refrigerated Warehouses.” February 12, 2007. March 31, 2009. http://www.treehugger.com/files/2007/02/night_wind_proj.php
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FAQ

1. What is an off-peak cooling system?

An off-peak cooling system is a cooling system that takes advantage of lower electricity rates during off-peak hours to cool a building. This type of system is usually set up to operate during the night, when electricity rates are lower, and the cool air can be stored in the building for use during the day.

2. How does an off-peak cooling system work?

An off-peak cooling system works by using a thermal storage unit, such as a large tank of water or a phase-change material, to store cool air during off-peak hours. During the day, the cool air is circulated through the building using fans or ductwork, providing cooling without requiring the use of energy-intensive air conditioning units.

3. What are the benefits of using an off-peak cooling system?

The benefits of using an off-peak cooling system include lower energy costs, reduced peak demand on the electric grid, and increased energy efficiency. This type of system can also help to reduce greenhouse gas emissions and improve indoor air quality by reducing the need for traditional air conditioning units.

4. Can an off-peak cooling system be used in all types of buildings?

Off-peak cooling systems can be used in a variety of building types, including residential, commercial, and industrial buildings. However, the feasibility of using this type of system will depend on factors such as the size and layout of the building, local energy rates, and the availability of thermal storage units.

5. How much does it cost to install an off-peak cooling system?

The cost of installing an off-peak cooling system will depend on a variety of factors, including the size of the building, the type of thermal storage unit used, and the complexity of the installation. However, in general, off-peak cooling systems are less expensive to install than traditional air conditioning systems, and can provide significant long-term savings on energy costs.

6. Are off-peak cooling systems reliable?

Off-peak cooling systems are generally reliable, as long as they are properly installed and maintained. However, like any other type of cooling system, they may experience occasional downtime or require repairs or maintenance over time.

7. How long does it take to install an off-peak cooling system?

The time required to install an off-peak cooling system will depend on the size and complexity of the installation. In general, however, installation can usually be completed within a few weeks to a few months.

8. What kind of maintenance is required for an off-peak cooling system?

The maintenance requirements for an off-peak cooling system will depend on the specific system and components used. However, typical maintenance tasks may include regular cleaning of the thermal storage unit, inspection and cleaning of ductwork and fans, and checking and replacing filters as needed.

9. Are there any incentives or rebates available for installing an off-peak cooling system?

Many utility companies and government agencies offer incentives and rebates for the installation of energy-efficient cooling systems, including off-peak cooling systems. These incentives can help to offset the cost of installation and make it more affordable for building owners and managers. Additionally, the long-term energy savings provided by these systems can help to recoup the initial investment over time.

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