Elsevier

Biomass and Bioenergy

Volume 47, December 2012, Pages 459-468
Biomass and Bioenergy

Temperature dataloggers as stove use monitors (SUMs): Field methods and signal analysis

https://doi.org/10.1016/j.biombioe.2012.09.003Get rights and content

Abstract

We report the field methodology of a 32-month monitoring study with temperature dataloggers as Stove Use Monitors (SUMs) to quantify usage of biomass cookstoves in 80 households of rural Guatemala. The SUMs were deployed in two stoves types: a well-operating chimney cookstove and the traditional open-cookfire. We recorded a total of 31,112 days from all chimney cookstoves, with a 10% data loss rate. To count meals and determine daily use of the stoves we implemented a peak selection algorithm based on the instantaneous derivatives and the statistical long-term behavior of the stove and ambient temperature signals. Positive peaks with onset and decay slopes exceeding predefined thresholds were identified as “fueling events”, the minimum unit of stove use. Adjacent fueling events detected within a fixed-time window were clustered in single “cooking events” or “meals”. The observed means of the population usage were: 89.4% days in use from all cookstoves and days monitored, 2.44 meals per day and 2.98 fueling events. We found that at this study site a single temperature threshold from the annual distribution of daily ambient temperatures was sufficient to differentiate days of use with 0.97 sensitivity and 0.95 specificity compared to the peak selection algorithm. With adequate placement, standardized data collection protocols and careful data management the SUMs can provide objective stove-use data with resolution, accuracy and level of detail not possible before. The SUMs enable unobtrusive monitoring of stove-use behavior and its systematic evaluation with stove performance parameters of air pollution, fuel consumption and climate-altering emissions.

Highlights

► Small, unobtrusive temperature dataloggers were used as Stove Use Monitors (SUMs). ► We measured with SUMs sustained use of 80 chimney stoves in Guatemala for 2.6 years. ► To count meals we analyzed slopes and statistics of stove and ambient temperature signals. ► SUMs require standardized placement, data management and validated analysis algorithms. ► SUMs give objective stove-use data with unparalleled resolution, accuracy and detail.

Introduction

We define “Stove Use Monitors” (SUMs) as devices that objectively quantify stove use through direct measurements of physical or chemical parameters (temperature, heat flux, light, current, motion, gas concentrations, etc.) on stoves, kitchens, cookware or food. A “Stove Use Monitoring System” (SUM-System) is defined as a platform of tools including SUMs, device readout, data transmission and storage interfaces, data analysis algorithm, database management and reporting tools for the systematic study of stove adoption and use. We previously used small temperature loggers as SUMs [1] to document the initial adoption of chimney stoves by rural households in Guatemala. In this paper, we followed an extended group of 80 homes from the RESPIRE/CRECER stove trial [2], [3] from January 2008–November 2010 and recorded temperature signals from their chimney cookstoves during 16 monitoring periods of 28 days each (a total of 31,112 stove-days) in alternating months and from a subgroup of traditional open-cookfires. In this paper we report the data collection protocols for both types of stoves, but focus on the analysis methods to obtain measures of daily use and meal frequency from the chimney-stove temperature signals.

Section snippets

Temperature datalogger characteristics

We used the Thermochron iButtons 1921G (Maxim Integrated Products, Sunnyvale, CA) as SUMs. These devices enclose a silicon temperature sensor, a memory, a signal processing circuitry and a battery in a stainless steel can that has the size and appearance of a coin cell battery (Fig. 1B). This model operates between −40 °C and 85 °C, and can record up to 2048 temperature and date-time readings with ±1 °C accuracy. Communication with the sensors to program them or download data is by momentary

Analysis of the chimney-cookstove temperature measurements

The temperature of the stoves that are not in use is expected to closely follow the indoor kitchen temperature, which in turn will be a function of the interaction of ambient temperature with the kitchen structural characteristics and the potential presence of another cookstove or cookfire (the only heating sources used in the region). This is illustrated in Fig. 5 which shows the bimodal distributions of daily maximum Fig. 5A) and daily mean (Fig. 5B) cookstove temperatures of the 30,122

Conclusions

In this paper, we assessed the field performance of small low-cost temperature dataloggers as SUMs and implemented an algorithm to obtain counts of the daily meals cooked. We found that with adequate placement, standardized data collection and careful data management the SUMs can provide objective and unobtrusive data of stove use with resolution accuracy and level of detail not possible before. This new tool promises to enable systematic and scalable monitoring of the stove adoption process,

Acknowledgments

We are in debt to the Guatemalan families in the RESPIRE and CRECER studies who patiently let us into their homes and daily lives. We thank the extraordinary dedication and commitment of all the staff and fieldworkers. In particular, we are grateful to: Biol. Carolina Romero Orellana for her logistic support in the field and valuable assistance with project management, Rudinio Acevedo for valuable assistance with database management, Edgar Coronado for field assistance, Nick Lam for fruitful

References (14)

There are more references available in the full text version of this article.

Cited by (70)

View all citing articles on Scopus
View full text