**7.3. Life cycle assessment**

• *Organics*. The most common are biphenyl/diphenyl oxide, which is a mixture of biphenyl

• *Molten salts*. They have stability at high temperature (greater than 500 °C); they also have properties comparable to water at high temperature, such as viscosity and low vapor pres-

• *Liquid metals*. They have promising properties such as extensive operating temperature range, low viscosity, and efficient heat transfer characteristics. As a reference, liquid so-

Nowadays, the topic of global warming has become a top trending around the world. Life cycle assessment (LCA) was created in 1960. It is a tool to evaluate the environmental impacts and is an instrument to help take decisions, ecodesign, and comparative of alternatives. This section shows a comparasion of environmental performance of air-conditioning absorption system with conventional air-conditioning system by LCA according to international laws ISO 14040 and ISO 14044.

The air-conditioning absorption solar system (*ACASS*) considered for this study is installed as a prototype on the Research Center in Engineering and Applied Sciences (CIICAp) of the Autonomous University of the State of Morelos (UAEM), located in Cuernavaca, Mexico, with a warm subhumid climate. In this place, March, April, and May are the warmest months during the year, thus the required demand of air-conditioning increases, with an average per day

The capacity of *ACASS* installed is 17.6 kW such as providing air-conditioning for five offices. The design temperature average was proposed around 23°C, which is considered the comfort temperature. The system will be employed from Monday to Friday, during March to May,

A plant of cylindrical-parabolic collectors that generate 26.44 kW was installed to drive the cycle, and 12 photovoltaic panels have been coupled to ACASS to generate 1.89 kW and supply electrical energy to the auxiliary devices that require it, covering 98.9% of the demand. Twenty-five years was considered as the useful period, according to the literature review [55].

This study considers a window-type conventional air conditioning (CAC) of 3.52 kW of capacity, and average energy demand is 1300 W. The operations conditions and useful life are considered for both systems; therefore, 12.5 units of 39.34 kg in average was evaluated. These

units have a lifespan of 10 years according to the literature review [56].

, respectively [54].

sure. Most of them are based on nitrates/nitrites, but salt production is restricted.

dium has an operating temperature range between 98°C and 833°C.

**7. Comparison of the environmental performance of a solar airconditioning system vs a conventional electrical system, using LCA**

(C12H10) and diphenyl oxide (C12H10O).

58 Sustainable Air Conditioning Systems

**7.1. The solar system description**

solar radiation of 7.31, 6.85, and 6.16 kWh/m<sup>2</sup>

with a schedule from 11:00 to 16:00.

**7.2. Conventional air-conditioning system**

According to the international standards ISO 14040 and 14044, LCA is defined as the assessment of the environmental impacts associated with a product, process, or service throughout their life cycle, tied in closely with the paradigm of "cradle to grave." This methodology consists of four phases, which can cross-interact at any point of the assessment, as shown in **Figure 7**.
