Residential Air Conditioning Electricity Monitoring

Speeches Shim

This field study of air conditioning units in Sonora, Mexico provides strong evidence supporting uptake of high-efficiency units. Results may also help in designing effective incentive programs and construction codes.

Energy efficiency policies support important goals in developing countries, such as reducing fuel imports, reducing energy cost burdens in low-income households, and reducing power sector capital requirements to meet increasing electricity demand. Adoption of energy efficiency technologies usually requires an up-front investment by consumers that pays off over time in the form of lowered energy bills.

Policymakers need to demonstrate both the cost-effectiveness of the investment and the relevance of the policy for national goals. For this reason, credible data about energy use, markets for technology, and related costs are indispensable components of technical analysis. Unfortunately, these data are often scarce in developing countries, posing a significant barrier to effective policy development.

Mexico’s Technology Threshold

Mexico has a long history of successful energy efficiency programs for appliances, including minimum energy performance standards (MEPS) and financial incentives, and each of these has included residential air conditioners in their scope. Currently, baseline level residential air conditioner energy efficiency in Mexico lies at an important technology threshold, beyond which both energy efficiency and price increase significantly. In recognition of the critical role that data characterizing residential air conditioner energy use could have in informing government action in Mexico, USAID undertook a dedicated technical assistance project to begin to close this data gap.

During the summer of 2019, through its Energy Efficiency for Development program, USAID conducted a pioneering direct measurement of residential air conditioners in the state of Sonora, Mexico, where summer temperatures routinely approach 105ºF. While residential air conditioners are the subject of MEPS in Mexico, to date, these regulations have not specifically required the use of an important efficiency technology—variable-speed, or “inverter” units—due to uncertainties about net financial benefits to consumers. USAID’s measurements help to clarify this picture, and may also be helpful in designing effective financial incentive programs and construction codes to increase insulation.

Mexico Cooling Summit

In 2018, USAID and Berkeley Lab organized a Mexico Cooling Summit to discuss the impact of air conditioning growth and potential mitigations options. Berkeley Lab presented macro-level analysis of 2016 seasonal and regional electricity trends confirming that:

  1. The residential sector contributes the most to summer electricity use,
  2. Use is highly concentrated in the north of the country, and
  3. A cooling peak, suspected to be residential in origin, is evident in the late night and early morning hours.

One output of the summit included a Mexico Cooling Initiative incorporating multiple strategies for reducing air conditioner electricity consumption, including:

  1. Minimum energy performance standards (MEPS),
  2. Incentive programs,
  3. Building codes,
  4. Solar-reflective surfaces, and
  5. Advanced technologies and controls.

During the Mexico Cooling Summit, data scarcity was identified as a key barrier to energy efficiency success in that country.

Sonora Field Study

On average, Mexican households only use about 1,000 kWh of electricity per year due to the mild climate in the densely-populated Central Valley, which includes Mexico City. In the hot northern and coastal areas, however, air conditioning use can force consumption to more than twice this amount. Previously, only rough estimates have been made of electricity consumption due to air conditioning use based on assumptions and surveys of typical use patterns.

To provide a more direct measurement of air conditioner electricity consumption, USAID’s partnered with Xinampa, Inc., a California-based technology startup, and the Sustainability Department of the State of Sonora (SEDES) to measure consumption by households in Sonora’s largest city, Hermosillo. The research team collaborated with a local air conditioning contractor and installer to identify 20 participating households. Xinampa installed electricity meters directly into air conditioner circuits and indoor temperature sensors, and paired these with distributed sensor networks to remotely gather high time-resolution data from June through September thereby capturing the majority of the 2019 summer season.

While limited in scope, this study succeeded in helping SEDES and the National Energy Efficiency Commission better understand how air conditioning is used in Mexico and created a critical dataset that can be used to provide an evidence base for future programs.

Conclusions and Implications

This project is representative of ways in which technical assistance can provide expert advice in developing specific policies and programs, as well as support key datasets that underpin energy efficiency efforts, thus removing an important information barrier. Specifically, the study provided credible evidence of two critical factors: high use and nighttime peak.

High Use

Most importantly, the study provides the first-ever field measurement of electricity consumption of minisplit air conditioners in Mexican households. Over the summer, all measured units used more than 500 kWh, and more than half used over 1,000 kWh. Adjusting for the cooler months of May and October, which were not directly measured, estimated average annual air conditioner use is 1,277 kWh, placing a high economic burden on families, most of whom own more than one air conditioner. It is well-known that electricity bills can be dramatically lowered through the use of inverter-type air conditioners, but these models command only a small fraction of the market due to a price premium of about 3,000 pesos ($150 USD). This investment becomes cost-effective if usage is more than 750 kWh per year. Between 500 kWh-750 kWh per year, inverters are cost effective when taking account of the cost of government electricity subsidies. The study therefore provides strong evidence supporting uptake of high-efficiency inverter air conditioners in Mexico, at least in Sonora. The data suggests that in the highest-use households, efficient equipment pays for itself over time, and even for many lower-use households, a government subsidy on equipment would produce net benefits.

Nighttime Peak

The confirmation of the late-night air conditioning peak points to a potential stumbling block in Mexico’s energy transition, and possibly a way to deal with it. Most of Mexico’s clean energy strategy to date has relied on a rapid transition to solar electricity, which is abundant and so far performs favorably in reverse auctions relative to wind and natural gas plants. Since solar electricity is not directly available at night, the nighttime residential cooling peak poses a serious problem, unless electricity storage is scaled up significantly.

Aggressive energy efficiency adoption can help reduce high electricity bills of Mexican households that use air conditioners and alleviate the barrier to cleaner electricity production posed by growing air conditioner use. While mass adoption of inverter-type air conditioners is an aspirational goal of Mexican policymakers, clear evidence of cost-effectiveness now exists. The Sonora field study plays a crucial role in the development of energy efficiency policies, including mandatory regulations, cross-subsidies, and awareness campaigns.

USAID’s Energy Efficiency for Development (EE4D) program provides technical assistance to USAID partner countries to scale up clean energy and energy efficiency rapidly and effectively. USAID partners with the Lawrence Berkeley National Laboratory to provide technical assistance to energy system planners, regulators, and utility managers in partner countries to overcome challenges associated with implementing energy efficiency programs. Berkeley Lab works with local stakeholders to identify areas of greatest opportunity, gaps, and barriers in order to better integrate energy efficiency as a resource for sustainable development.

Tuesday, November 17, 2020 - 1:15am