**4. Analysis of the proposed options for an ITV workshop**

This section compares the energy performance of various options for air conditioning a wide-open workshop. Starting from an initial situation (option 0) of a non conditioned building, its energy consumption once refurbished is studied and compared for each of the three following options: an air curtain system functioning as a climate separator (option 1); the previous system with a conventional air handling unit (option 2); and finally, a comprehensive air conditioning system of high efficiency that includes all aspects covered by section 2 and 3 of this chapter.

The design of this system and the selection of components for the case study are due to Eng. Paul Gerard O'Donohoe, who has used technology developed by TAYRA S.L.

To analyze the performance of the technical systems for each of the proposed situations, a representative industrial building has been selected. Such is the case of a wide-open workshop, where technical assessments of roadworthiness are carried out on cars and trucks (ITV workshop). This type of buildings is of rectangular shape, with a surface area of 1620 m2 and a height of 7.5 m. It has no windows, but five entrances and exits, three of them at 5 m x 3 m and two at 5 m x 4.5 m. The exit doors are controlled to limit the flow of vehicles leaving the premises. These buildings, that outnumber 1,000 all around Spain, are usually located in remote areas just off main motorways. For the case study, an ITV workshop located in Carmona (Sevilla) was chosen. See attached plan in Figure 9.

**Figure 9.** ITV workshop in Carmona (Seville). Plan

124 Energy Efficiency – The Innovative Ways for Smart Energy, the Future Towards Modern Utilities

production is also suggested, but not discussed in this chapter.

**3.4. Primary air conditioning unit** 

**Figure 7.** EQUAM adiabatic air handling unit

**Figure 8.** Psycrometric processes of indirect adiabatic cooling

**4. Analysis of the proposed options for an ITV workshop** 

This section compares the energy performance of various options for air conditioning a wide-open workshop. Starting from an initial situation (option 0) of a non conditioned building, its energy consumption once refurbished is studied and compared for each of the

conditions and EX for exhaust air.

With the obtained values, accomplishment of normative comfort conditions is tested, paying special attention to the temperature difference between head and feet (ASHRAE, 1992).

Ventilation is provided by a primary air handling unit with indirect adiabatic cooling heat exchanger section (Figure 7). The unit has two water coils. The heat coil is supplied by the heat production system described in section 3.2. The cooling load is met by water from a compression chiller. An alternative system with a solar absorption chiller for cold

Air transformations in the air handling unit components are shown in the psycrometric chart (Figure 8), where O stands for outdoor air, S for air supplied to the coil, R for room

> Using a computer simulation of the building with the e-Quest program (Figure 10), a prediction of its performance for the aforementioned options has been obtained. E-Quest uses DOE2 engine to perform an hourly simulation of the building for a whole one-year time period. For each hour, heating and cooling loads are calculated. The performance of pumps, fans, boilers, chillers and every energy consuming equipment within the building is also simulated. Finally, the energy use of every end use, including lightning, is tabulated. Authors such as Crawley et al. (2008) provide a sound comparative study of the potential offered by the most common simulation tools, DOE2 included.

High Efficiency Mix Energy System Design with Low Carbon Footprint for Wide-Open Workshops 127

• Two air curtains Indac S150 (Biddle) placed in series for each of the six existing doors

• Two air curtains Indac S200 (Biddle) placed in series for the two doors for large vehicles. Air curtains characteristics have been selected (Figures 11a and 11b) by using a commercial

**Figure 11.** a. Winter conditions air curtain selection, b. Summer conditions air curtain selection

They recirculate air at the room temperature throughout the year. The supplied air flow rate is fixed (5,000 m3/h), and the equipment adapts its velocity of discharge speed by varying the geometry of the outlet. Thus, an identical download length is achieved whatever the external conditions of wind are. The estimated electric power is 0.44 kW per curtain, giving

simulation program (Biddle Innovative Klimatechnik, 2012).

for small vehicles.

a total power of 7.04 kW.

**Figure 10.** ITV workshop in Carmona (Seville). E-Quest simulation

In the simulations, synthetic meteorological data have been used. 8.762 records, including hourly data, have been generated by the program CLIMED 1.3 (IDAE, 2009) from the normal data of AEMET for the meteorological station of Seville.

The aforementioned cases are described next:

#### **4.1. Case 0: Original building**

ITV workshops, for the reasons stated in the introduction, do not have any higrothermal conditioning system. Not even a mechanical ventilation system, as room air is changed by means of natural ventilation through permanently open doors. The energetic simulation in this conditions, only seeks to analyze the evolution of indoor temperatures throughout the year, in order to identify the times when it exceeds the limits allowed by labor legislation (16ºC in winter and 28ºC in summer).

The simulation of the building in its original condition reveals that the 56% of annual hours, indoor temperature remains outside the limits marked by labour legislation (Table 9).


**Table 9.** Annual distribution of hourly temperatures
