**4.2. Case 1: Air curtains as climate separators and mechanical extraction ventilation system**

The climate separation is achieved by means of the following equipment:


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

normal data of AEMET for the meteorological station of Seville.

The aforementioned cases are described next:

**4.1. Case 0: Original building** 

(16ºC in winter and 28ºC in summer).

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

**ventilation system** 

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

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

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).

**4.2. Case 1: Air curtains as climate separators and mechanical extraction** 

The climate separation is achieved by means of the following equipment:

Air curtains characteristics have been selected (Figures 11a and 11b) by using a commercial simulation program (Biddle Innovative Klimatechnik, 2012).

**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 a total power of 7.04 kW.

• A mechanical extraction system with an air flow rate of 70,000 m3/h, which is equivalent to 7 ACH, according to the most restrictive rate of ventilation indicated by current Spanish legislation (R.D. 314/2006, 2006b, 2006c; Ayuntamiento de Madrid, 1985).

High Efficiency Mix Energy System Design with Low Carbon Footprint for Wide-Open Workshops 129

The air curtains also function as terminal heating units that supply air at 27°C in winter conditions. Air conditioning is achieved in this case by a high efficiency system that includes

• A modular condensation gas boiler Tayra/Unical Eco-pacQ-Mx-550-CS2-EM with a power output of 228 kW (heat conversion efficiency: 108 %) meets the thermal loads

• A VRV air condensed water chiller with a power output of 57.1 kW, and estimated

• A EQUAM primary air handling unit (100% outside air) with the following characteristics: Supply and return fans air flow rate is 30,000 m3/h (7 ACH for a 3 m height, that corresponds to the occupied zone); A 28 kW heating coil, running on hot water (50/35ºC), supplies air at 19ºC, maintaining the outdoor specific humidity conditions; A 46.7 kW cooling coil, running on chilled water (7/12ºC) supplies air at 24ºC and 78% relative humidity; A cross flow heat recovery unit (70% average efficiency), with a heat recovery capacity of 151 kW for nominal flow in winter conditions (0.6 ºC y 90% relative humidity), provides a supply air at 16.2 ºC from the extract conditions (19ºC and 26% RH); in summer conditions heat recovery capacity is 161.6 kW, for it includes an adiabatic cooling by water sprays of extract air at 24ºC and 78% relative humidity. By means of this indirect adiabatic cooling, outside air at 40ºC y 24% de HR, is brought to

• A displacement air diffusion system, with 13 diffusers VA-ZDA DN 355, of Kranz Componenten, suspended at 3 m height in the position indicated in Figure 9. The throw distance is 9 m, when nominal flow is supplied, with a sound power level of 63 dBA. They incorporate a device for regulating the discharge, which can change its direction upwards or downwards depending on the regime conditions (cooling or heating). The return is by ceiling, but some grids at floor level help to remove heavier

With this system, air is supplied at 26ºC in winter to keep indoor conditions close to 28ºC. This indoor project temperature, combined with residual air velocities higher than usual but acceptable due to the physical activity of the workers, allows to keep comfort conditions in the occupied zone. Furthermore, high temperatures that are obtained in the ceiling may be

The simulation of the case 3 yields the monthly evolution of electrical and fuel

demanded by air curtains (25 kW each) and the air handling unit coil (28 kW). • A solar thermal installation is design to provide 70% of the energy requirements for heating. It has been chosen a 24 m2 surface of collectors ASTERSA AT020 (optical efficiency: 0.748 and heat loss factors: 3.718 and 0.014 W/m2K) oriented South and inclined at 35º, that transfer the collected thermal energy to a 3,000 liters storage

**4.4. Case 3: Air curtains and a high efficiency HVAC system** 

tank.

seasonal EER is 3.5.

contaminants.

all the strategies that have been described in section 2 and 3 of the chapter:

28.7ºC and 59% relative humidity before entering the water coil.

used with high efficiency in the heat recovery process.

consumptions that are shown in Figures 14a and b:

The simulation of the case 1 yields the monthly evolution of electric consumptions that are shown in Figure 12:

**Figure 12.** Case 1: Monthly electric consumption

## **4.3. Case 2: Air curtains and a conventional HVAC system**

The climate separators described in the previous option also function as terminal heating units that supply air at 27°C in winter conditions. They are completed with a conventional air conditioning system comprising:


The energy simulation of the building and its technical system leads to results of monthly electric and fuel consumption that will be compared in the next section with the results for the more efficient option 3.

The simulation of the case 2 yields the monthly evolution of electrical and fuel consumption that is shown in Figures 13a and b:

## **4.4. Case 3: Air curtains and a high efficiency HVAC system**

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

shown in Figure 12:

**Figure 12.** Case 1: Monthly electric consumption

air conditioning system comprising:

and 14ºC, respectively.

seasonal EER of 3.5.

the more efficient option 3.

that is shown in Figures 13a and b:

handling unit heating coil (183 kW).

**4.3. Case 2: Air curtains and a conventional HVAC system** 

• A mechanical extraction system with an air flow rate of 70,000 m3/h, which is equivalent to 7 ACH, according to the most restrictive rate of ventilation indicated by current

Spanish legislation (R.D. 314/2006, 2006b, 2006c; Ayuntamiento de Madrid, 1985).

The simulation of the case 1 yields the monthly evolution of electric consumptions that are

The climate separators described in the previous option also function as terminal heating units that supply air at 27°C in winter conditions. They are completed with a conventional

• A primary air handling unit that supplies a volume air flow rate of 7 ACH which. Considering that the whole volume of air in the building is renewed, the air flow rate comes to 70,000 m3/h. Winter indoor temperature is 18ºC, while, during the summer, temperature is kept to 26ºC. They are obtained with supply air from the unit at 30ºC

• A gas boiler with a power output of 700 kW (estimated seasonal efficiency: 86%), meet the heating loads demanded by the air curtains (47,7 kW each) and the primary air

• A VRV air condensed water chiller with a power output of 218.1 kW, with an estimated

The energy simulation of the building and its technical system leads to results of monthly electric and fuel consumption that will be compared in the next section with the results for

The simulation of the case 2 yields the monthly evolution of electrical and fuel consumption

The air curtains also function as terminal heating units that supply air at 27°C in winter conditions. Air conditioning is achieved in this case by a high efficiency system that includes all the strategies that have been described in section 2 and 3 of the chapter:


With this system, air is supplied at 26ºC in winter to keep indoor conditions close to 28ºC. This indoor project temperature, combined with residual air velocities higher than usual but acceptable due to the physical activity of the workers, allows to keep comfort conditions in the occupied zone. Furthermore, high temperatures that are obtained in the ceiling may be used with high efficiency in the heat recovery process.

The simulation of the case 3 yields the monthly evolution of electrical and fuel consumptions that are shown in Figures 14a and b:

High Efficiency Mix Energy System Design with Low Carbon Footprint for Wide-Open Workshops 131

In the absence of air conditioning system, the predicted indoor temperature evolution throughout the year suggests that there is significant potential for intervention to improve

For what respects to the more efficient system to air conditioning a wide open workshop, the analysis of the energy consumption during a year simulation allows to conclude that high efficient system like the proposed, composed by a solar heating installation with a condensing gas boiler auxiliary power option, air curtains for environmental thermal control and displacement ventilation supplied by a dedicated outdoor air handling unit with evaporative indirect cooling, reduces electric consumption to 37% and gas consumption to

From the point of view of its efficiency, it is highlighted the importance of the general conception of the system, instead of placing design efforts in improving the performance of

The comparison between systems should be done in terms of primary energy and carbon emissions, rather than based on economic criteria. European legislation states that a system of energy performance certification is a mandatory requirement for rented, sold or constructed buildings. In response to this, Spain's recent building regulations have established the process of certification of new buildings. A series of tools are provided to calculate whether the new buildings are highly efficient (class A) or least energetically efficient (class G). The official program used for this process of certification is called CALENER and provides an average carbon value of the overall building energy performance, and classifies it by means of a comparison of the performance of the building

systems and construction materials with their corresponding reference values.

Tomas Gil-Lopez, Miguel A. Galvez-Huerta, Juan Castejon-Navas and Paul O'Donohoe

We wish to thank Virginia Gomez-Garcia and TAYRA S.L. for the invaluable contribution to this chapter (the whole conception of the HVAC proposed system and the selection of design parameters during the simulation). In this respect we specially thank David García

ACGIH (1999). Threshold Limit Values and biological exposure indices, *American Conference of Governmental Industrial Hygienists*, Spanish version: Valores límite para sustancias

(Plenum Ingenieros S.L.P.), who has meticulously carried out the simulation process.

**5. Conclusion** 

its components.

**Author details** 

**Acknowledgement** 

**6. References** 

the performance of the activities in ITV workshops.

35%, compared to a conventional HVAC system.

*Madrid Polytechnic University ,Tayra S.L., Spain* 

**Figure 13.** a. Case 2: Monthly electric consumption, b. Case 2: Monthly gas consumption

**Figure 14.** a. Case 3: Monthly electric consumption, b. Case 3: Monthly gas consumption
