246,000 people (CBS, 2022a; ICIMOD, 2019a). A brief snapshot of Nepal’s brick industry is summarized in Table 1.

**Table 1: Snapshot of Nepal’s brick industry**

|Parameter|Year|Value|Data Source|
|---|---|---|---|
|Number of brick kilns|2018|1,349|(ICIMOD, 2019a)|
|Distribution of kilns by province<sup>a</sup>|2018|P1 (8.8%), P2 (30.2%), P3 (21.2%),<br>P4 (6.4%), P5 (23.4%) and P7 (9.8%)|(ILO et al., 2020)|
|Annual production|2018|5.14 billion|(ICIMOD, 2019a)|
|Value of annual output<sup>b</sup>|2020|NRs 14 billion|(CBS, 2022a)|
|Contribution to GDP|2020|4%|(CBS, 2022a)|
|Coal consumption|2018|504,750 tons|(ICIMOD, 2019a)|
|CO2emissions|2016|2.2 million tons|(Eil et al., 2020)|
|Total industry employment<sup>c</sup>|2018|186,150|(ILO et al., 2020)|
|Brick price index (2015=100)|2021|127|(CBS, 2022b)|
|AAGR<sup>d</sup>of the construction industry|2013-22|6.3%|(CBS, 2022b)|

_Notes_ :<sup>a</sup> P1 is Koshi, P2 is Madesh, P3 is Bagmati, P4 is Gandaki, P5 is Lumbini and P7 is Sudurpachim provinces. Karnali province reported only 2 kilns in the operation.<sup>b</sup> Based on the sum of three national classifications of industrial codes (NSIC), i.e., 2391, 2392, and 2393.<sup>c</sup> Out of total employment, 95% are manual workers and 5% are administrative workers. About half of the manual workers are of Indian origin. The total brick industry employment represents about 17% of the country’s total manufacturing industry workforce.<sup>d</sup> AAGR is the average annual growth rate.

The basic types of brick kilns for firing clay bricks in Nepal are the clamp kiln (CK), fixed chimney bull’s trench kiln (FC BTK), improved zigzag kiln (ZZK), vertical shaft brick kiln (VSBK), Hoffman kiln (HK), and tunnel kiln (TK). These kilns can be classified as _traditional_ or _modern_ kilns.<sup>12</sup> However, traditional kilns dominate all kilns, representing about 76% of all kilns (ICIMOD, 2019a). Among these types of brick kilns, the CK and FC BTK are the least energy efficient and most polluting while the TK is the most energy efficient and least polluting. It is possible that FC BTKs can be upgraded to improved ZZKs because of the similarity in their technical designs. However, very few FC BTK are converted to ZZK kilns due to a lack of skilled

> capacity ranging from 15,000 to 50,000 bricks per day, Eil et al. (2020) reported 1,595 kilns producing 4.9 billion bricks in 2016, and DOI (2022) reported total number of registered kilns since 1993 as 1,577 at the end of 2018 and CBS (2022a) reported 1,008 registered brick kilns in 2018 but their information on how many of them are in operation is not available. Many factors contribute to these wide variations in the number of kilns, such as the operation of several non-registered brick kilns around the country, and poor government documentation.

> 12 There are several classifications of clay-fired brick kilns, e.g., intermittent, and continuous kilns based on the production process, up-draught, down-draft, and cross-draft kilns based on airflow, and natural and induced or forced draft kilns based on the method of production Kumar and Maithel (2016). We classify brick kilns as either _traditional_ or _modern_ based on the combination of kiln technology differentiated by their specific energy consumption (SEC), i.e., the energy required in MJ to produce 1 kg of clay-fired brick, the quality of brick produced, brick quality, labor productivity, and emissions. In this study, six brick kilns are considered that are operated in Nepal. Two of these six kilns (CK and FC BTK) are considered as _traditional_ kilns and the remaining four (ZZK, VSBK, HK and TK) are considered as _modern_ kilns. Note that modern kilns have better SEC (fuel efficiency) and lower emissions, better brick quality and higher labor productivity than the traditional kilns. Similar terminologies are used by Eil et al. (2020). We consider ZZK, which is an improved and retrofitted version of FC BTK, as _modern_ , because it can potentially achieve greater fuel efficiency due to optimized airflow and reduced heat loss (Maithel et al., 2013; Tibrewal et al., 2023).

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