Improving water heaters for sustainability

Buildings use about 40% of the total U.S. energy demand. Water heaters provide hot water for a variety of building uses including sinks, showers, dishwashers, washing machines, and space heating. Water heaters are the second most energy intensive appliances in a common household. Typically a home water heater's energy sources is natural gas. There are other types of tank water heaters including ultra low NOx, and electric resistance. Figure 1 displays the differences in water heater types. Electric resistance water heaters use electrical grid power. Building owners burdent thec cost of water heating through the initial water heater cost, energy bills, and the communal air pollution they breathe. Burning and extracting non-renewable fuels including natural gas leads to climate change. Water heaters noticeably attribute air pollution to winter inversions have adverse affects on human health. Combusted air pollutants include Carbon Dioxide (CO2), Nitorgen oxides (NOx), and Sulfur oxides (SOx). Pushing towards the future Salt Lake City has set a goal to reduce 80% of green house gases emissions by the year 2040 setting a demand for water heater emissions reduction.

Improving Water Heaters for Sustainability Nicholas Malinowski University of Utah Dr. Amanda D. Smith University of Utah I.  IntroducAon Buildings use about 40% of the total U.S. energy demand. Water heaters provide hot water for a variety of building uses including sinks, showers, dishwashers, washing machines, and space heaAng. Water heaters are the second most energy intensive appliances in a common household. Typically a home water heater's energy source is natural gas. There are other types of tank water heaters include ultra low NOx, and electric resistance. Figure 1 displays the differences in water heater types. Electric resistance water heaters use electrical grid power. Building owners burden the cost of water heaAng through the iniAal water heater cost, energy bills, and the communal air polluAon they breathe. Burning and extracAng non-renewable fuels including natural gas leads to climate change. Water heaters noAceably aLribute air polluAon to winter inversions have adverse affects on human health. Combusted air pollutants include Carbon Dioxide (CO2), Nitrogen oxides (N0x), and Sulfur oxides (SOx). Pushing towards the future Salt Lake City has set a goal to reduce 80% of green house gases emissions by the year 2040 seUng a demand for water heater emissions reducAon. II. Methods III. Results This research aims to quanAfy energy and emissions effects for various water heaters. EnergyPlus a building modeling so[ware uAlizes a comprehensive building informaAon file and locaAon specific weather file to perform an annual energy demand simulaAon for a buildings hot water usage delivered by a water heaAng system. Modelkit so[ware was used to perform mulAple EnergyPlus calculaAons at once with modified variables for water heater fuel source type, and thermal efficiency. Matlab coding so[ware inputs the water heater energy demand data to numerically and graphically analyze energy usage, and emissions on various Ame scales. The results in figure 2 and 3 show annual water heater energy consumpAon and savings per week for water heaters with efficiencies ranging from 90 to 95%. All trends display the matching water heater efficiency delivering the same amount of energy to the water. Week 6 during winter is the highest demand for water heaAng during the year and week 34 in the summer is the lowest demand for water heaAng. Figure 4 and 5 display annual water heater emissions and savings per week for water heaters with efficiencies ranging from 90 to 95%. The CO2 emissions are the dominaAng trends for both water heater types. The electric water heaters generate more CO2 with the current Salt Lake City electricity grid. Emissions for NOx, and SOx appear in small amounts at the boLom of the graphs. Figure 2 & 3 - Annual Water Heater Energy Figure 4 & 5 - Annual Water Heater ConsumpAon and Savings Per Week Emissions Generated and Saved Per Week Table 1 - Water Heater Values IV. Conclusions A case-by-case basis is the best way to correctly size the right equipment for a buildings hot water demand. The graphs demonstrate for both water heater fuel sources types an increase of thermal efficiency, decreases the energy consumpAon, decreases the emissions, and increases the energy and emission savings. The water heaters CO2 emissions are relaAvely high compared to NOx , and SOx emissions. Electric resistance water heaters produce more CO2 with the current electricity grid. Increasing the efficiency of an electric resistance water heater has a larger effect of reducing CO2 emissions compared to a natural gas. Electric water heaters give the opAon for building electrificaAon. V. Future Work Figure 1 - Electric Resistance and Natural Gas Water Heaters Model hybrid tank water heater equipment with EnergyPlus. UAlize real building water heater energy usage to perform calculaAons for esAmate implicaAons of water heater choices. Acknowledgements / References: This work was supported by the University of Utah Office of Undergraduate Research. Use of data was supported by the U.S. Department of Energy for building files and EnergyPlus for weather files. The Modelkit program used was developed by Big Ladder So[ware. The water heater diagram was located from www.agendadepaznarino.com Nicholas Malinowski University of Utah Mechanical Engineering [e-mail]