• DMUSD Energy Use Report

    February 21, 2018

    In 2014, AESC performed energy audits at eight campuses in the Del Mar Unified School District through the SDG&E Audit Program. Throughout 2015, the District worked with AESC to make use of Proposition 39 funding, in addition to the utility incentives, to implement upgrades to save energy, decrease utility expenses, and improve student and faculty comfort. As of August of 2015, these eight campuses completed projects addressing lighting, HVAC, and controls systems. In order to verify the benefits of the projects, AESC performed a billing analysis to track the change in electricity consumption between 2014 and 2018. 

    The energy efficiency projects entailed the installation of:

    • 10,000 new LED lamps and fixtures at seven sites,
    • Dimmable controls or occupancy sensors for lighting in selected areas,
    • An upgraded Energy Management System (EMS) for increasing HVAC performance by improving scheduling, limiting demand, and adopting nights and weekend setbacks,
    • New high efficiency air conditioning package units at the Carmel Del Mar school. 

    An analysis was completed for January 2014 through December 2014 and January 2015 through December 2017 to provide an assessment of the energy consumed before and after the installation of the energy efficiency projects. The schools saw an energy savings of 20,305 kWh in 2015, 151,985 kWh in 2016, and 212,474 kWh in 2017 when compared to consumption from January 2014 through December 2014. Therefore, the school district saw an energy savings of 384,764 kWh and cost savings of $52,251 from January 2015 through December 2017. Charts 1 and 2 illustrate the electricity consumption of the school district for the aforementioned periods. 

    Chart 1 Comparative Electricity Consumption

    chart 1  

    Chart 2 Electricity Consumption and Costs

    chart 2  

    Weather normalization accounts for the different weather conditions under which the schools operated in between 2014 through 2017; data normalization is a common practice in energy engineering and analysis. Weather normalization with cooling degree days[1] (CDD) was an important step in the analysis of determining the normalized electricity consumption. With cooler temperatures, electricity consumption for heating, ventilation, and air-conditioning (HVAC) should be reduced from the previous year as shown in the chart below. Chart 3 summarizes the cooling degree days throughout the year for the school district.  

    Chart 3 Cooling Degree Days Summary

    chart 3

    [1] Cooling degree days are defined as the sum of the difference between outside air temperature and 65°F for each hour of the year when the outside temperature is above 65°F divided by 24. 

    Between January and December in 2014, the school district consumed 2,649,344 kWh of electricity costing $813,487; whereas it cost the district $889,687 for 2,629,039 kWh in 2015, $708,560 for 2,497,359 kWh in 2016, and $789,964 for 2,436,870 kWh in 2017 respectively. The overall decrease of 20,305 kWh in 2015 resulted in an increase of electricity costs by $76,199 due to increase in electricity rates in 2015. This phenomenon is best illustrated in Chart 4 which shows the electricity prices for the two above-mentioned time periods. 2016 saw a lower price per kWh and which resulted in the previously noted cost savings. Although 2017 saw an increase in the average price per kWh, the total cost of electricity decreased from 2014 due to significant decrease in consumption. The average price per kWh for January 2014 through December 2014 was $0.307 compared to $0.333 per kWh in the calendar year 2015, $0.283 per kWh in 2016, and 0.323 per kWh in 2017.

     Chart 4 Electricity Prices Comparison

    chart 4  

    Table 1 Annual Energy Consumption and Savings

    table 1

    DMUSD saved a total of 384,764 kWh from January 2015 through December 2017 as previously noted, and as shown in Table 1.