19.2.1 The Cost-Optimal Methodology and Consolidated Indexes for Evaluating the Feasibility of Energy Projects

In the matter of reduction of greenhouse emissions and with the aim of a more rational use of energy of EU countries, several documents have been enacted by the EU Institutions starting from the 2002. In this brief overview, only the main ones will be analyzed, from the previously cited European Directive 2010/31/EC “Directive of the European Parliament and of the Council of 19 May 2010 on the Energy Performance of Buildings” (European Council and Parliament, 2010), to the last document that came into force after the Conference of Paris 2015 (the 2015 United Nations Climate Change Conference). Starting from this last event, this chapter has been written just few days after the ending of the 2015 United Nations Climate Change Conference, the so-called COP21, hosted in Paris in December 2015. The Conference has established a satisfactory agreement and historical document subscribed to by 195 countries worldwide. Indeed, the objectives of Paris—and these are something more than intentions, more like kind of program—may be defined as the end of the era of fossil fuels, by orienting, at the global level, the next future toward an established “threshold of salvation.” It was well known that, to maintain the life on Earth, the average temperature increase compared to preindustrial levels should be kept below 2°C. To that end, the COP21 fixed a more ambitious target, by stopping the increase at 1.5°C by 2020. Furthermore, the COP21 identified significant funding measures and a precise path that includes the required balance between greenhouse gas emissions and storage, the revision of targets every 5 years, and mandatory intended nationally determined contributions (INDCs), which give a measure of the effort assumed by each country.

It is quite difficult to give an exact number of the impact of the building sector on the present energy demands of countries at the global level; for sure, a reasonable impact can be identified around 35–40%. Finally, by taking into account the high share of energy requests of the present building stock (a significant part of which is made up of ancient buildings, at least in Europe), the energy retrofit of the existing buildings, as well as the ones characterized by historical values, is mandatory, if the identified goals would be seriously achieved.

After the significant steps by the construction sector in the direction of European energy efficiency, starting from the EPBD 2002/91/EC (which has an epochal impact, by concerning the mandatory energy refurbishment of the existing buildings, if renovated, and the obligations to energy labels), after some years, the EPBD Recast (European Council and Parliament, 2010) inferred some important new targets. In particular, Article 9 (Paragraph 1) established that by December 31, 2020, all new buildings must demand nearly zero energy, and an important demonstrative role has been attributed to buildings occupied and/or owned by public authorities. In fact, these have to reach the goal of nearly zero energy 2 years earlier, in January 2019.

As said, it is well known that the turnover rate of buildings throughout the EU is quite low, so that an energy efficiency program that does not take into account the existing building stock cannot be effective. To that end, Directive 2012/27/EU (EU Commission and Parliament) established, for EU member states, “a long-term strategy for mobilizing investment in the renovation of the national stock of residential and commercial buildings, both public and private.” Moreover, this document, received all around Europe by specific laws (In Italy, by D.M. 102/2014 (Italian Government, 2014)) introduces:

The same “Exemplary role of public bodies’ buildings” is newly affirmed in Article 5. Indeed, it is established that “each Member State shall ensure that, as from 1 January 2014, 3% of the total floor area of heated and/or cooled buildings owned and occupied by its central government is renovated each year to meet at least the minimum energy performance requirements.”

This book chapter is framed just into this cornice. We will show two case studies owned by public institutions, and thus all proposed feasibility studies, beyond the technical and economic profitability, could also serve as examples of responsibility and best practices by the public hand, by fully fulfilling the role that the res publica has to have in all issues concerning the public life.

In order to favor, promote, and, definitively, to facilitate these targets, the energy efficiency of both private and public buildings, with reference to the thermal envelope, active energy systems for the microclimatic control, building appliances, lighting systems, and systems and equipment for the energy conversion from renewables, have been largely funded (Italian Ministerial Decree DM 28/12/12, 2013; European Regional Development Fund ERDF), in the last 10 years, by Italian institutions. Beyond the national system of incentives, other important programs have been funded directly by the EU institutions (Interregional Operational Program (POI), 2007/2013; Ascione et al., 2014a), such as, for instance, the Interregional Operational Program (POI) dedicated to energy efficiency actions and renewable installations in some European regions (i.e., the so-called “convergence areas”). Really, in order to be exemplar, the public funding has to be used in the most useful way to be profitable for all involved stakeholders, first of all the citizens that, more or less directly, support (through the general tax system) all these measures. Moreover, the same citizens are directly involved by the effects of renovations, being interested in both a better quality of life inside these buildings and a better urban environment due to lower emissions and reduction of urban heat islands.

Finally, before the implementation of an EEM, proper studies have to be performed to evaluate its profitability and appropriateness. In the next subsection, first the standard approach is proposed, and then the new methodology—the so-called “cost-optimal” approach, introduced by the EPBD Recast—is suitably described. According to consolidated approaches for evaluating the convenience in applying EEMs—e.g., actions concerning the thermal envelope of a building, systems and equipment for air conditioning (and thus both for the space heating and cooling), and energy systems for conversion from onsite renewables—the following indicators are usually evaluated:

Really, as the first step, the simple payback period (SPB) should be evaluated to immediately detect the most cost-effective ECMs.

$\Delta \text{EP}={\text{EP}}_{\text{BB}}-{\text{EP}}_{\text{ECM}}$ (19.1)

(19.1)

$\Delta \text{OC}={\text{OC}}_{\text{BB}}-{\text{OC}}_{\text{ECM}}$ (19.2)

(19.2)

$\Delta \text{PE}={\text{PE}}_{\text{BB}}-{\text{PE}}_{\text{ECM}}$ (19.3)

(19.3)

$\text{DPB}=N:{\displaystyle \sum _{i\text{=1}}^N\frac{F_i}{{(\text{1+}{R}_{\text{d}})}^i}}=C_{\text{I}}$ (19.4)

(19.4)

$\text{NPV}={\displaystyle \sum _{i=1}^{\text{LF}}\frac{F_i}{{(1+R_{\text{d}})}^i}}-C_{\text{I}}$ (19.5)

(19.5)

$\text{IP}=\frac{{\text{NPV}}_{20}}{C_{\text{I}}}$ (19.6)

(19.6)

In the above-reported equations, the following terms are:

Moreover, the subscripts BB and ECM are used for referring to the base (present) building and the refurbished one, respectively, according to the applied ECM.

Many examples of investigations that apply the aforementioned indicators are available in the matter of energy efficiency for buildings and technical feasibility of ECMs, as, for instance, for building thermal envelopes (Ascione et al., 2013c,d, 2014a), or for the overall energy demand of the entire facility (Hassoun, 2014; Galvin and Sunnkka-Blank, 2012; Chaiyat and Kiatsiriroat, 2014; Ascione et al., 2011b).

In order to give, at least with reference to the countries of the European Community, a codified approach, the EPBD Recast (European Council and Parliament, 2010) introduced a different and more homogenous procedure, the so-called “cost-optimal” methodology. This approach can be applied to all building designs, with reference to new constructions and renovations, for each single ECM or package of these. More in detail, the global cost (C_g), referred to the building lifetime, is calculated as exhaustively described in EU Commission (2012), by applying the algorithm proposed in Eq. (19.7). In this, τ is the calculation period, C_I is the initial investment, C_a,i are the operational costs during the year i for the measure or set of measures j, R_d is the discounting factor and V_f,τ is the residual value of measure at the end of the calculation period.

$C_{\text{g}}(\tau )=C_{\text{I}}+{\displaystyle \sum _j\left[{\displaystyle \sum _{i=1}^{\tau }\left(C_{\text{a},i}(j)\times R_{\text{d}}(i)\right)-V_{\text{f},\tau }(j)}\right]}$ (19.7)

(19.7)

The real interest rate and the energy price escalation have to be varied, in order to have a sensitivity with respect to their evolution. Moreover, the annual energy demand is assumed constant along the calculation period, which is set equal to 20 years, as recommended for nonresidential buildings, and 30 years for dwellings (BPIE, 2013). All told, the global cost C_g takes into consideration each expenditure during the calculation horizon, and, therefore, investment, replacement costs, and operational costs.

19.2.1.1 Tailored Energy Investigations: Transient Energy Simulations and Calibrated Building Models

According to the various approaches to the building numerical simulations, the energy calculations can be carried out in various ways, by applying steady-state or transient energy balances, by taking into account conventional, reliable, or real boundary conditions, with reference to climate, building use, and input data concerning the indoor set-points and so on. To that end, a general overview of possible ratings is provided by the standards EN 15603 (CEN—European Committee for Standardization, 2008) and EN 13790 (ISO, 2008), in which four possibilities are identified:

 Design rating: The calculations are performed by adopting input information derived from the building design. The boundary conditions related to the building use and climate are standard, and the scope of the calculation is the achievement of the building permit or the redaction of the energy label.

 Asset rating: This is similar to the previous one; the main difference concerns the input data. In this case, the information is derived by analogy with similar buildings, direct surveys, inspections, and in situ probes, such as thermography or heat flux measurements for evaluating the envelope conductance or the presence of thermal bridges.

 Tailored rating: The boundary conditions are specified with reference to the single building just investigated. Indeed, the required outcome is not a conventional energy performance, but a reliable building energy behavior, in order to identify criticalities, opportunity of renovations, and feasibility of adoption of EEMs. This approach is not suitable for the building energy labeling (because too many degrees of freedom are available for the simulation), but for a realistic or reliable analysis of a particular building.

 Operational rating: This is a kind of energy signature of the building and, therefore, the evaluated energy performance is calculated starting from real measurements of energy requests (energy billings).

It is quite clear that, if the aim is a deep investigation of the building energy performance, with reference to a specific edifice, the “tailored rating” has to be applied. That is, the transient energy simulation is much more suitable and precise compared to methods based on steady-state heat transfer algorithms. Briefly, dynamic (or transient) energy calculations take into account heat-storage phenomena in the building envelope, so that the heat transfer through an element is the result of the present forcing phenomena, as well as of the previous temperatures’ and heat flows’ differences through the same component. More in detail, the inertial effect of mass, specific heat, and insulation are taken into consideration, so that important phenomena, such as the time lag effect, decrement and attenuation of the heat wave, the start-up of the active energy systems and, analogously, the time constant of the building, can be exhaustively contemplated. Of course, various algorithms for evaluating the heat transfer can be adopted, and thus, only the ones offered by the program used here are cited (i.e., EnergyPlus 7.2 and 8.0, Energy Plus Simulation Software, 2013):

 conduction transfer function algorithms (CTF)

 conduction finite differences algorithms (ConFD)

 combined heat and moisture finite element algorithms (HAMT).

The CTF method relates the heat flux, through the envelope element, to the current and previous internal and external temperatures and to the previous values of heat flows. The methodology is very powerful and fast, because the nodal temperatures are not calculated, so the method does not require the discretization of the walls in several nodes. On the other hand, ConFDs provide completely the spatial heat transfer through the building surfaces, by identifying the temperatures at each node of the thermal envelope, so that the thermal field is completely determined. Compared to CTF, the required calculation power is higher, as well as the simulation time. The HAMT algorithm, finally, allows the contemporary evaluation of vapor and heat transfers, by solving simultaneously transportation and storage of moisture and energy.

Normally, the CTFs are the most used algorithm, even if particular situations—such as the evaluation of proper melting temperature of phase change materials or investigations of strategies for solving problems of interstitial condensation—can require, respectively, adoption of ConFD or HAMT. Beyond the solution algorithm, the number of time steps per hour is also important. This is the time interval between two consecutive energy balances and, normally, it ranges from 2 to 60 per hour.

Once the energy model is defined as accurately as possible (with reference to geometry, thermophysical properties of the layers of each structure of the building thermal envelope, definition of systems and equipment for air conditioning, artificial lighting, profiles of use, set-point, and so on), when possible, the main outcomes of the energy simulations should be compared with real onsite measurements. Indeed, a calibrated present scenario is the base for testing, numerically, the profitability of energy refurbishment, according to the previously cited indicators of feasibility or through the newer methodology of cost optimality. Usually calibrations for energy simulations are carried out by means of the calculation of the following indicators (M&V Guidelines, U.S. Department of Energy, November 2015):

 Mean bias errors (MBE) (Eq. 19.8). This indicator shows “how well the energy consumption is predicted by the model as compared to the measured data” (U.S. Department of Energy, November 2015).

 Coefficient of variation (Eq. 19.9) of the root mean squared error CV(RMSE)

$\text{MBE(\%)}=\frac{{{\displaystyle {\sum }_{\text{period}}(\text{M}-\text{S})}}_{\text{time basis}}}{{\displaystyle {\sum }_{\text{period}}{\text{M}}_{\text{time basis}}}}\times 100$ (19.8)

(19.8)

${\text{CV(RMSE}}_{\text{month}}\text{)(\%)}=\frac{{\text{RMSE}}_{\text{time basis}}}{{\text{A}}_{\text{time basis}}}\times 100$ (19.9)

(19.9)

In Eqs. (19.8) and (19.9), M and S are respectively the monitored and simulated energy demands, while RMSE is the root mean squared error and A is the average value of the monitored energy consumption. The time basis can be the month or the hour. According to the ASHRAE Guideline 14-2015 (ASHRAE, 2015), acceptable calibration tolerances, according to monthly values, are MBE within ±5%, CV(RMSE) within 15%.

19.3.1 Climate of South Italy: Coastline and Backcountry

Benevento is located in the southern part of the Italian peninsula; the weather is generally moderate, with warm summers and not-so-cold winters. In detail, the climatic conditions are typical of an interior (e.g., backcountry) Mediterranean area, with mild winters and dry, hot summers. The city is classified Csa, according to the Köppen-Geiger standard (Peel et al., 2007). Annually, the average air temperature has been around 15.1°C, with an annual value of rain around 780 mm. Compared to Naples, lying just on the Tyrrenian coast, the climate of Benevento is colder, because of the lower solar radiation and, mainly in summer, the general conditions are less favorable even if the temperatures are lower. Indeed, the morphology of the site and the presence of two significant rivers imply air stagnancy and quite high values of relative humidity. Conversely, Naples, on the coastline, has a warm Mediterranean climate, with many more rainy days during the winter compared to the summer season, and an annual temperature of 15.8°C and around 900 mm of rain. For both cities, the month characterized by the highest rainfall is November, while July is the warmest and most arid month. Annually, Naples has a slightly higher rainfall.

More information about the average monthly values of air temperature, solar irradiance, rain, and air relative humidity, for both cities (to evidence the differences between Mediterranean backcountry and coastline) and climates, is reported in Fig. 19.3A–D, respectively. It can be seen that Benevento is slightly colder, mainly because of the backcountry position and the proximity of the Taburno Camposauro, a great massif, with a maximum height of 1350 m. Definitively, we are in the area of the Apennine Mountains, which, as a kind of spinal column, cuts Italy from north to south, just in the middle.

19.3.2 Description of Buildings

The public hand, and thus the University of Sannio (Palazzo San Domenico) and the local train service (Appia Railway Station in Benevento) own the buildings here analyzed. Moreover, both buildings have a public function, being used for service of the tertiary sector (respectively, education and transport). The first building is characterized by historical and cultural values, while the second one, after the reconstruction in 1987, can be classified as a normal building without cultural peculiarities. Beyond the age and the value of cultural good, other significant differences concern dimensions, hosted functions, building technologies, and so on. All these issues, as shown in the following sections, will affect both the approach to the energy refurbishment (for instance, some refurbishment options have been automatically excluded, due to invasiveness, for Palazzo San Domenico) and the feasibility, in quality and quantity, of the proposed ECMs.

19.3.2.1 Palazzo San Domenico in Benevento

The building (Fig. 19.4) hosts the main administration of the University of Sannio, as well as the Rectorate of the Institution and some valuable rooms used for the graduation ceremonies (graph 19.4d). Palazzo San Domenico has a quite stratified construction development, starting from the 12th century and, over the centuries, it was renovated many times according to various architectural styles. It is located just in the heart of the historical center of Benevento. Originally, it was used for religious purposes. At now, in the present configuration, it has a rectangular shape, three usable floors above the ground, a global height, by excluding the sloped attic, of about 18 m, a volume of around 23,725 m³. The air-conditioned area is equal to 3220 m² (it should be noted that a further 3006 m² are not equipped with heating systems).

Several surveys and inspections revealed a very complex composition of the building envelope, due to the many refurbishments along the various phases and uses of the building. Mainly, the vertical structure is made in blocks of tuff and heterogeneous stones. The average thicknesses of the envelope are very high, with average values, at the ground floor, even equal to 1.60 m. Also with reference to the horizontal structures, and thus slab on the ground, ceilings, floors, and roofs, there is a great variety of composition, being present vaults and mortar, wooden beams, recent concrete joints, and masonry blocks. The presence of windows is generally limited, around 6% of the gross vertical facades. Recently, all old windows have been replaced with double-glazed systems, argon-filled cavities, and wooden frame. The main information concerning the thermophysics is reported in Table 19.1A.

Table 19.1

Description of the case study buildings: geometry, thermophysical properties, active energy systems

(A) Palazzo San Domenico in Benevento		(B) Appia Railway Station in Benevento
Construction age	Starting from 12th century	Construction age	Rebuilt in 1987
Use	Office and university events	Use	Railroad station
Conditioned area	3220 m2	Conditioned area	1321 m2
Gross volume	23,725 m3	Gross volume	4776 m3
Vertical walls	Masonry, high thickness U = 0.52 W/m2 K	Vertical walls	Double layer of hollow bricks, 4 cm of EPS, U = 0.48 W/m2 K
Net wall area	3454 m2	Net wall area	1204 m2
Windows	Double layer, argon filled U = 2.9 W/m2 K	Windows	Double layer (4/12/4), air filled U = 2.7 W/m2 K
Windows area	220 m2	Windows area	374 m2
Windows/wall	6.0%	Windows/wall	21.4%
Slab on the ground	Wood, concrete, vaults, U = 1.41 W/m2 K	Slab on the ground	Slightly insulated mixed structures, joists and bricks, U = 0.74 W/m2 K
Roof	Mixed composition, with wood, concrete, vaults, U = 1.60 W/m2 K	Roof	Slightly insulated structures, concrete joists and bricks, U = 0.75 W/m2 K
Heating systems	Mixed air/water systems (two rooms) and hydronic systems with fan coils	Heating systems	Not centralized, individual stand-alone DX systems in some spaces
Cooling system	Not centralized, individual stand-alone systems in some spaces	Cooling system	Not centralized, individual stand-alone systems in some spaces
Boilers	Two hot-water gas boilers, η = 92% Nominal heating capacity = 479 kW	Boilers	Presently not installed
Chillers	Not centralized, few autonomous DX systems are installed in some rooms	Chillers	Not installed, autonomous DX systems are installed in some rooms

The building has a centralized control of the heating system, consisting of fan coils units fueled with hot water produced by a centralized generation system (two gas boilers, gas fired). To provide control of air quality in some crowded spaces, two conference rooms have mixed air/water HVAC systems, with a contemporary presence of fan coils and air terminals, and this system allows also the control of latent loads. With reference to the artificial lighting, mainly halogen and fluorescent lamps are installed.

19.3.2.2 Appia Railway Station

This architecture is not ancient, having been completely rebuilt in 1987, after the destruction of the ancient building by the November 1980 Irpinia earthquake. The station is located just on the Appia, one of the consular roman roads, which connects Rome with Brindisi. The road was built in the Roman period for military use. The role of the Appia Railway Station, even if it is not the main station in Benevento, is strategic, as it is closest to the city center and thus highly used by students and workers coming from Naples (Napoli) and from the province of Benevento. Beyond this, the station also has some technical blocks and hangars, used for train maintenance.

From an energy behavior standpoint, the present building was completed around 30 years ago, when legislation regarding energy efficiency in buildings was not yet exhaustive and the respect of few and not-strict prescriptions was enough to obtain a building permit. Finally, as it will become clear in the next sections, the building is quite energy inefficient. The Appia Railway Station is quite simple, characterized by three stories above the ground and one partially buried. Two main blocks are connected by means of a covered passage, a kind of connection from the parking to the tracks. The second block is a single-story edifice. In Fig. 19.5, an overview of the building is proposed. The technology of construction is typical of Italian (really, European) building stock dated after World War II, and thus consisting of a structural frame of reinforced concrete with walls made up of double layers of hollow blocks. Ceilings, roofs, and slabs have a mixed composition, with reinforced concrete and lightweight bricks. More in detail, the external walls of the envelope have plastered hollow blocks with an interposed cavity and external insulation of 4 cm of polystyrene. For the ceiling, floors, and roofs, a mixed structure (reinforced concrete for beams and joists, interposed hollow bricks) is realized, with an upper layer of lightweight concrete and few centimeters of thermal insulation lying under the external coating. All windows have plastic frames and double glasses, with an air-filled cavity (U_W=2.72 W/m² K, SHGC equal to 0.76). The physical composition of the thermal envelope is shown in Fig. 19.5C–F.

The building area is around 1332 m² (1321 m² that need to be air-conditioned) with newsstand, cafeteria, tobacconist, ticket office, waiting room, and technical office for the train service control at the ground floor, and offices on the first and second floors as well as in the second building block. The global volume of the building is around 4776 m³, with an overall height of 15.0 m (main block, staircase), 11.2 m (main block, roof of the third floor), and 4.7 m (second block, single story).

With reference to the heating and cooling systems, the Appia Railway Station has many autonomous direct expansion devices (even if many areas, such as staircases, common spaces, corridors, and passages are neither heated nor cooled). More in detail, the building is not equipped with a centralized HVAC plant. Indeed, recently, the hot-water gas combustion boiler and in-room radiators have been removed. At the same time, the air changes are exclusively achieved by means of natural ventilation through the opening of windows and doors.

All thermophysical properties (calculated by means of the numerical approach, by the standard 6946, ISO 6946, 2007) and other technical specifications are provided in Table 19.1B.

19.4.1 Present Buildings: Modeling and Calibration

Palazzo San Domenico was divided, with reference to the numerical model, in a number of homogenous areas, diversified depending on the specific use, position, and exposure. According to the information acquired onsite, the building model has many thermal zones, as meeting rooms, offices, corridors and services, technical service rooms, classrooms. Beyond a number-of-person (i.e., occupancy rate) variable depending on the kind of use of the specific room, the metabolic rate has also been diversified, depending on the typical hosted function.

According to the Whole-Building Level Calibration with Monthly Data approach, described by the M&V and ASHRAE Guidelines (U.S. Department of Energy, 2015; ASHRAE, 2015), a quite satisfactory correspondence between simulations and measurements has been found. In detail, the primary energy demands for heating (EP_H) and the overall electric energy demand for all building uses (E_EL) have been calculated, by comparing simulations and measurements. The cited indexes of calibration, and thus the mean bias error (MBE) and the coefficient of variation of the root mean squared error CV(RMSE), are (on an annual basis):

It should be noted that, because of some maintenance problems, the building was also heated during the weekends. Globally, the comparisons between monitoring and predictions revealed a fully acceptable correspondence, also taking into account other studies concerning large buildings as the one here described.

For Palazzo San Domenico, a first necessary EEM already has been taken into consideration, i.e., the upgrade of the present heating system, in order to be able to also provide space cooling. Indeed, it was found, by simulating the present building and also by verifying these results with the opinion of the occupants, that for about 82% of the summer hours, the indoor air has a temperature higher than 26°C. Very often the temperature is in the range 28–35°C, so that this basic first upgrade has been considered. Therefore, once calibrated the simulation, this first energy measure was applied. This consists of the adoption of a hydronic air-conditioning system with new four-pipe fan coils, suitable for both space heating and cooling. The hot water is produced by the present gas boiler (nominal efficiency of 0.92), while the chilled water is provided by a new air-cooled chiller (energy efficiency ratio, at rated conditions, equal to 3.0 W_TH/W_EL). The domestic hot water was supplied by electric boilers, placed in the bathrooms. The basic cost for this system, parametrically evaluated, is around 421,730 €, according to the Italian market (2016) and by excluding the gas boiler already installed.

Regarding the Appia Railway Station, all input data have been assigned by numerically evaluating thicknesses and characteristics of materials, once particular criticalities have been investigated (i.e., thermal bridges, air leakages) by means of in situ investigations and thermography (Fig. 19.6). Indeed, energy billings were not available, so that a calibration of the numerical model, ex-post, was not possible. Regarding the definition of thermal zones, according to the various hosted functions, several typologies have been created, with variable boundary conditions depending on the use (office, waiting rooms, commercial spaces, etc.). The gains due to equipment, as well as the occupancy rate, installed lighting level, and infiltration rates have been assigned consequently.

Also for the Appia Railway Station, a basic upgrade of the present systems for air conditioning has been taken into consideration immediately. Indeed, the presently installed direct expansion (DX) systems absolutely cannot satisfy the thermal comfort requirements, either in winter or summer, so that a new mixed air/water system has been designed. More in detail, new fan coils provide, in each room, the control of temperature (i.e., sensible heat loads), while the primary (i.e., outdoor) air, after the treatments in an air-handling unit (AHU), allows the control of indoor humidity (i.e., latent loads), by providing the needed air changes for indoor air quality (IAQ). The design of HVAC systems has required the definition of 46 different thermal zones, because of the different boundary conditions, above all in terms of the necessary amount of outdoor air for allowing a satisfactory indoor quality. To that end, the indications of the EN 15251 (CEN (European Committee for Standardization), EN 15251, 2007) have been taken into consideration, so that there is a fixed amount related to the room area, plus an additional quantity depending on the occupancy rate. All told, a dedicated outdoor air system (DOAS), for controlling the humidity conditions and the quantity of outdoor air, has been coupled to the fan coils for temperature control. As said, the system is turned on during occupancy hours, and thus from 8 a.m. to 6 p.m., for 7 days/week in some zones (e.g., waiting rooms, bars, cafeteria), and for 5 days/week in all office spaces. For this basic renovation of the HVAC system, the estimated cost is 195,000 €. This investment takes into consideration the entire plant, and thus also a high-efficiency hot-water boiler and an air-cooled chiller.

For both buildings, as typical in Italy, two set-point temperatures have been defined, during the operating hours of the active energy systems for the microclimatic control, as 20°C during the heating period and 26°C for the space cooling. When allowed, in both seasons, the relative humidity control has been fixed at a set-point of 50%, for both the heating and cooling seasons. Moreover, both buildings are in Italian Climatic Zone C, with a conventional heating period as established by law from November 16 to March 31. Conversely, the cooling period is not fixed, but the cooling starts to operate when—for some consecutive days—the indoor temperatures are higher than 26°C. Usually, depending on the amount of solar and internal gains, this period goes from May to September even if, also in October, some cooling hours could be necessary on particular days. Because of the kind of use of buildings and according to the Italian regulations for Climate Zone C, in both cases we considered an operational time for microclimatic control from 8 a.m. to 6 p.m. The model calibrations, as cited, have been carried out in two different ways. For the Appia Railway Station, indeed, the calibration concerned mainly the input of the numerical model, as it was not available in the energy bills.

Thus, thermography, careful inspections, and measures with heat-flow meters have been carried out. More in detail, in Fig. 19.6, some thermographs of the building have been reported. These reveal high infiltrations from windows, due to the poor airtightness of the present components, as well as the significant heat losses of the staircase, above all due to the large glazed area (Fig. 19.6F). On the other hand, no significant thermal bridges have been detected, because of the continuous layer of thermal insulation (Fig. 19.6A–C), even if only a few centimeters are installed. These studies have been performed during winter 2014 and all surveyed data have been used to model the base case building and thus to calibrate the input of the simulation model.

_________________

By considering the base case, and thus the present scenario, the outcomes reported in Fig. 19.7 have been calculated, for both Palazzo San Domenico and Appia Railway Station. It should be specified that, for both buildings, the present scenario (i.e., reference case) developed in Fig. 19.7 is not the present configuration. Indeed, as previously cited, for both Palazzo San Domenico and the Appia Railway Station, a first upgrade of the heating and cooling systems has been considered necessary. In other words, without these interventions, no thermal comfort can be achieved, so that these should be intended as necessary actions and not as ECMs. Once these new designs of active energy systems have been provided, the energy performances of the present buildings are simulated in EnergyPlus (Fig. 19.7), according to the following boundary conditions:

To elaborate the data, the following parameters, costs, and coefficients of emissions have been considered:

The outcomes, reported for a unitary floor area in order to be comparable, are compared in Fig. 19.7, with reference to the monthly energy demands for heating and humidification (Graph A), cooling and dehumidification (Graph B), monthly overall electric requests (Graph C), and annual energy demand for HVAC uses (Graph D).

It should be noted that, with reference to the Appia Railway Station, the energy uses also consider the electric energy demands for humidification and dehumidification. Indeed, given the high occupancy, the humidity control is necessary as well as the mechanical air changes.

The energy demand for heating of the historical building is lower, due to the high thicknesses of masonry (so that the global thermal transmittance is acceptable, as inferred in Table 19.1) but mainly because of the very low amount of windows. Moreover, the high contribution of the lighting system (low efficiency and largely used, given the small transparent surfaces) is also significant. In those terms, as it will be shown in the next sections, an ECM will be applied also to the lamps. At the same time, the absence of mechanical ventilation allows lower energy losses, even if the indoor air quality cannot be properly controlled. On the other hand, given the kind of use of the buildings, the energy demand for cooling of Palazzo San Domenico is higher in June and July (full use of buildings for didactic activities), while in August there is a decrease due to the summer holidays. For the Appia Railway Station, the free cooling achievable at many hours (thanks to the mechanical ventilation, in the early morning and during the second part of the afternoon) and the lower use of lighting (because of the large windows) allow a lower specific energy demand for cooling. On the other hand, since an air-handling unit that provides fresh air to the entire building is installed, the annual energy demand for fans is higher. Regarding the heating period, the large transparent surfaces of the Appia Railway Station imply significant energy losses, and thus the heating energy demand is higher.

19.4.2 Discussion: Energy Demands of the Reference Buildings

The investigation of the buildings in the reference scenario underlines some deep differences, namely the high energy requests for cooling due to internal gains (old lamps and equipment for the lighting of a low-fenestrated building) in Palazzo San Domenico, and the high demand for heating of a badly insulated building, the Appia Railway Station, mainly because of the large windows. Moreover, with reference to this second building, the ventilation loads during the heating season also induce high energy losses.

19.4.2.1 Palazzo San Domenico in Benevento

To evaluate the general profitability of suitable ECMs, as previously cited, a first modification is required, and thus the installation of a system aimed at improving the indoor comfort in summer conditions. Therefore, as a base case, we have considered not the base building but the one characterized by the installation of a simple hydronic air-conditioning system. More in detail, four-pipe fan coils run during both the heating and cooling seasons. It should be noted that, in the base case system, there is also a significant energy demand for heating satisfied by additional devices based on DX technology. Indeed, in some rooms (mainly offices), this equipment had been installed to integrate the energy supply and, where present and well-functioning, was not replaced by fan coils. All told, in the base case configurations, the following energy demands, costs, and polluting emissions connected to the need of microclimatic control have been considered:

 space heating (winter): energy demand equal to 152,270 kWh_PRIMARY (EP_H = 47.3 kWh_PRIMARY/m²a), energy costs around 14,773 €, polluting emissions of about 38.2 tons CO_2-equiv/year

 space cooling (summer): energy demand equal to 157,265 kWh_PRIMARY (EP_C = 48.8 kWh_PRIMARY/m²a), energy costs around 16,928 €, polluting emissions of about 51.2 tons CO_2-equiv/year.

Finally, to keep the indoor environment at comfortable conditions, both during the heating and cooling periods, energy costs of about 31,701 €/year are necessary, with related polluting emissions equal to 89.5 tons/year in terms of equivalent carbon dioxide. To improve the aforementioned indicators, the following EEMs have been investigated:

 Thermal insulation (TI) of the vertical walls, by means of the application of 5.0 cm of thermal plaster, thermal conductivity of 0.075 W/m K on the inner faces of wall. This also requires a suitable vapor barrier. The present thermal transmittance, equal to 0.52 W/m² K, can be lowered until 0.42 W/m² K. Of course, traditional external insulating layers cannot be considered for preservation reasons. The installation cost is 113,899 €.

 Thermal insulation of the roof (IR6), until a new thermal transmittance of 0.42 W/m² K. This requires the application of expanded polystyrene (IR6), with a thickness of 6.0 cm (λ = 0.035 W/m K). The overall cost is 57,006 €.

 Thermal insulation of the roof (IR8), with a new thermal transmittance of 0.27 W/m² K. This requires the application of 8 cm of polyurethane panels (with very low λ = 0.026 W/m K). The overall cost is 77,598 €, but this can be funded at 40% (Italian Government, 2012), by means of public incentives.

 Installation of new windows (LE), double glazed (3/13/3), with argon-filled air cavity, low-emissive coating. The frame is wood on the internal side, aluminum on the outer one. The U_W is equal to 2.6 W/m² K (SGHC = 0.743). The overall cost is 167,328 €. This kind of fenestration does not allow the achievement of public funding. However, it has been chosen because this is not invasive from the architectural point of view.

 Installation of a different type of windows (S), with a different double coating, low-emissive on the inner side, selective on the outer one. The frame is identical to the one above-described, U_W around 2.5 W/m² K (SGHC =0.430), investment cost of 172,323 €. Also this measure does not benefit from the public incentive.

 Installation of a new a DX variable refrigerant flow (VRF) system. In detail, two external DX units are installed, respectively with adsorbed electric power of 45 and 56 kW_EL (heating) and 50 and 63 kW_EL (cooling), and these supply thermal vector refrigerant to all coils for the space heating and cooling of the first and second floor. The solution is much less invasive compared to the one with a traditional air-to-water chiller, the in-room units are smaller compared to fan-coils, and the ducts can cross the existing false ceilings. At the ground floor, the present system is not replaced, given functional and logistical evaluations. The overall cost for this solution is 398,050 €.

The results of the feasibility study have been reported in Table 19.2. Please note that, with reference to the ECMs concerning the application of thermal plaster, thermal insulation for the roof with thickness equal to 6 cm, new fenestrations in both configurations, the public incentive cannot be obtained, because the achieved thermal transmittances are not respectful of the requirements established by Italian law.

Table 19.2

Palazzo San Domenico: Feasibility analysis of considered energy efficiency measures

ECM	ECM cost	Funding 40%	ΔEP		ΔOC		Δ CO2-equiv		DPB
	(€)	YES/NO	(kWh/year)	(%)	(€/Year)	(%)	Tons/year	(%)	(Years)
TI	113,899	No	11,682	−3.8	1161	−3.7	3.1	−3.5	>50
IR6	57,006	No	26,343	−8.5	2677	−8.4	7.5	−8.3	35
IR8	77,598	Yes	22,501	−7.3	2237	−7.1	6.0	−6.0	34
LE	167,328	No	27,378	−8.8	2685	−8.5	7.1	−7.9	>50
S	172,323	No	27,937	−9.0	2776	−8.8	7.5	−8.4	>50
VRF	−20,113	No	84,678	−27.4	8107	−25.6	20.5	−22.9	0

19.4.2.2 Appia Railway Station

The energy demands of the present building are quite high because of the high ventilation loads, in both seasons, as well as the necessity of control of latent loads, mainly in summer (i.e., it requires subcooling and reheating of outdoor air). Finally, the present building has an annual air-conditioning cost of about 15,759 € (9412 € winter season, 6347 € summer period), that induces CO_2-equiv emissions of about 24.8 tons during the heating period, 19.2 tons for space cooling. In terms of primary energy demands, and thus by taking into account suitable energy conversion factors, the requests are 73.0 kWh_PRIMARY/m²a (→96.0 MWh_PRIMARY) and 44.5 kWh_PRIMARY/m²a (→59.0 MWh_PRIMARY), with reference to the space heating and cooling, respectively. Starting from the aforementioned results, the following consolidated EEMs have been simulated to preliminarily identify the effects of energy efficiency actions for both the thermal envelope and the active energy systems (all costs are reported in Table 19.3):

 Further insulation of the opaque walls (TI), by means of additional 6.0 cm of EPS (flat panels). The thermal transmittance, equal to 0.48 W/m² K, becomes 0.28 W/m² K (−42%). This action can be funded at 40% (Italian Government, 2012).

 Further insulation, through additional 8.0 cm of EPS (IR8) of the roof slab. The thermal transmittance, equal to 0.75 W/m² K, becomes 0.30 W/m² K (−60%). This action cannot be funded because the required U_roof should be equal to or lower than 0.27 W/m² K.

 Replacement of windows (LE) with the adoption of low-emissive glass with a reflective coating. The present windows have a U_W of about 2.7 W/m² K. The new systems will have a U_W equal to 1.6 W/m² K (solar heat-gain coefficient (SHGC)=0.704). The refurbishment also concerns new wooden/aluminum frames and external shading systems with high-reflective slats, which can be automatically activated when the incident solar radiation is higher than 120 W/m². This ECM can be funded at 40% (maximum incentive of 45,000 €).

 A further ECM can be the replacement of windows only for the staircase block (SC-LE), where single-glazed systems are presently installed. The new system is identical to the ones above-described and equipped with reflective shading rolls (manually movable). Also this ECM can be promoted at 40%.

 Improvement of the airtightness of the building (AT), which can be achieved by means of replacement/installations of the windows’ seals. Presumably, this will allow the reduction of undesired infiltration from 0.75 ACH to 0.25 ACH.

 Because of the flat roof, roofing vegetation can be designed (green roof, or GR), aimed at reducing both energy requests for the space heating (i.e., lower convection on the outer side) and cooling (thanks to the evapotranspiration of soil and greenery and added thermal mass, and thus peak loads, moved during the night hours). An extensive green roof is investigated (C3 vegetation, height =25 cm, leaf area index =2.0 m²/m², stomatal resistance of vegetation =200 s/m, leaf reflectivity equal to 0.4). The estimated costs take into account the automatic irrigation system as well as the underlying thermal insulation. This ECM, provided with a suitable underlying insulating layer, can have an incentive of 40% (Italian Government, 2012).

 Selection of a condensing boiler (CO) (only the extra costs are taken into account), for providing low-temperature warm water to fan coils and coils of the AHU. The rated efficiency is 0.99. The 40% incentive can be achieved.

 Installation of sensible (η_S=0.75) and latent (η_L=0.70) heat recovery systems (HR) for the AHU. It should be specified that, with reference to the designed DOAS, the heat recovery is not mandatory according to Italian law with reference to this specific application, because the flow rates are low, and the climatic zone is not so cold.

Table 19.3

Appia Railway Station: Feasibility analysis of considered energy efficiency measures

ECM	ECM Cost	Funding 40%	ΔEP		ΔOC		Δ CO2-equiv		DPB
	(€)	YES/NO	(kWh/year)	(%)	(€/Year)	(%)	Tons/year	(%)	(Years)
TI	66,220	Yes	2857	−1.8	269	−1.7	0.66	−1.5	>40
IR8	26,129	No	4223	−2.7	406	−2.6	1.03	−2.4	>40
AT	13,896	No	17,223	−11.1	1641	−10.4	4.12	−9.4	≈9.9
LE	234,495	Partially	25,580	−16.5	2474	−15.7	6.37	−14.5	>40
SC-LE	27,770	Yes	7512	−4.8	737	−4.7	1.94	−4.4	≈38.1
GR	55,216	No	4985	−3.2	475	−3.0	1.21	−2.8	>40
CB	4985	No	15,355	−9.9	1412	−9.0	3.31	−7.5	≈3.8
HR	11,500	No	15,798	−10.2	1445	−9.8	4.05	−9.2	≈9.2

For what concerns the installation of low emissive glazing, the maximum incentive is 45,000 €, for the climatic zone C, in which Benevento is located.
In the results given by adoption of green roof, the artificial irrigation costs are not considered. This cost could be around 450 €/year, on the basis of the average monthly precipitation in Benevento, the runoff water, and by considering typical Italian water price.
About the adoption of a condensing boiler, the expenditure has been calculated as difference of price between that technology (200 kW) instead of a traditional boiler (high efficiency, low temperature) of the same size.

_________________________________

The results of the feasibility study are reported in Tables 19.2 and 19.3, for Palazzo San Domenico and the Appia Railway Station, respectively. The technical–economic evaluations have been developed by taking into account the initial expenditures and costs of operation. The calculated indexes of energy and economic feasibility are ΔEP (variation of energy demands), ΔPE (variation of polluting emissions), ΔOC (variation of annual operating costs), DPB (discounted payback, discounting factor R_d=3%/yearly). Please note that, as specified in the third columns of Tables 19.2 and 19.3, some EEMs can benefit, according to Italian law, from a funding equal to 40% of the full investment (Italian Government, 2012).

With reference to Table 19.3, it should noted that the cost for the artificial irrigation of the green roof is not taken into account. This cost can be quantified, by considering the average monthly precipitation of Benevento as well as the runoff of the soil and the characteristics of the vegetation, as around 450 €/year, with a unitary price of water equal to 1.3 €/m³. At the same time, it should be specified that, still with reference to Table 19.3, the evaluated cost for the installation of the condensing boiler is the difference between its cost (13,295 €) and that of a traditional combustion generator of the same size (high efficiency, low temperature, 200 kW capacity, 8310 €).

19.4.3 Results: Evaluation of Effectiveness of ECMs

With reference to both case studies, by comparing Tables 19.2 and 19.3, it can be noted that all EEMs applied to the building envelope are poorly feasible. Indeed, even if the energy costs can be reduced, adverse effects regarding the usefulness in heating and cooling modes can occur. First of all, it should be underlined that the buildings, even if they are far from being efficient, are not so poor in terms of energy performances in the present configuration. Indeed, Palazzo San Domenico compensates the absence of thermal insulation with the high thicknesses of the ancient building envelope. On the other hand, the Appia Railway Station already has some centimeters of thermal insulation, being built after the first Italian energy law for buildings, dated 1976. Moreover, as already anticipated, the energy benefits that can be achieved by adding thermal insulation provide contrasting effects in winter and in summer. For example, in Fig. 19.8, the energy demands for heating and cooling of the building as is and then refurbished by adopting thermal insulation of the roof, in two configurations, are compared.

For Palazzo San Domenico, it is quite evident that, by means of hyperinsulation of the roof, even if an obvious benefit occurs in terms of space-heating energy demand, the opposite effect happens in summer. Indeed, a phenomenon of indoor overheating implies a slightly higher energy demand for cooling compared to the building with a moderate insulation level (IR6). More in detail, by applying the insulation of the roof with 6 cm of EPS, the primary energy saving for the space heating is 13,783 kWh/year, while this saving is of about 16,033 kWh/year if 8 cm of polyurethane are installed. On the other hand, IR8 (8 cm of polyurethane) provides, compared to IR6, a greater energy demand for cooling (+6092 kWh/year) even if there is a savings of 6468 kWh/year compared to the base case without thermal insulation of the roof. It means that, after a certain threshold of thermal insulation, with reference to the summer performance, the energy demand for cooling increases again. In other words, the first centimeters of insulation, in a balanced climate, provide a benefit in reducing the cooling demand; after the first centimeters, the energy needs begin to increase (Fig. 19.8A).

This phenomenon occurs because the high thermal insulation, in summer, limits the energy losses (and thus the building thermal discharge during the nighttime, when the radiative cooling with the sky and the lower outdoor temperatures could allow a free cooling). In these terms, it is significant that, without insulation or with the highest level, there is a cooling demand also in May (Fig. 19.8A, right side). Conversely, with reference to the heating season, the more insulation there is, the better the energy performances are (Fig. 19.8A, left side). In our choice, we prefer the 8 cm of insulation with polyurethane, as the building is used mainly during the heating season. In other words, according to our consideration, we have given a higher weight to the season with the higher rate of occupancy. On the other hand, even if the energy demand in summer is slightly higher, in winter, beyond the energy benefits, a much higher indoor comfort can be achieved during the occupied hours (because of the higher radiant temperature of the ceiling of the top floor).

The same effect of hyperinsulation can be registered for the Appia Railway Station and a further new simulation has been performed for demonstrating it, with 10 cm of roof insulation (IR10). Finally, the best choice will be, according to the results of Tables 19.2 and 19.3 (and thus by taking into account economic considerations), no addition of insulation for the roof of station, 8 cm of insulation for the roof slab of Palazzo San Domenico.

For Palazzo San Domenico, with reference to the substitution of windows, both designed typologies (LE and S) do not provide significant benefits. Conversely, the adoption of a different system for heating and cooling, and thus a DX technology (VRF system) instead of the hydronic ones (i.e., the basic designed fan coils fueled by hot-water gas boilers and air-cooled chillers) is very effective. The proposed solution, beyond significant energy savings, also allows lower installation costs (no additional generators, but DX devices with the refrigerant flowing directly into the indoor units). In Tables 19.2 and 19.3, last column, a first criterion is shown for the selection of ECMs. In particular, here the most profitable actions (and thus the selected ones) are those that allow a DPB significantly lower compared to the lifetime of the ECM. In particular, these are:

In Fig. 19.9A and B, for Palazzo San Domenico and Appia Railway Station respectively, another criterion, merely economic, is used for verifying the appropriateness of the above-cited choices in terms of adoption of EEMs, and thus the cost of a single saved kWh of primary energy.

The adopted criterion established that an ECM is applied if the cost of the saved kWh is lower than 2 €. Regarding the adoption of VRF at Palazzo San Domenico, this is not shown in Fig. 19.9B because, compared to the base case, there is also a savings in investment, so that a discussion about the cost of saved kWh does not make sense. In Fig. 19.9B, it can be seen that the replacement of windows of the staircase of the Appia station is not strictly effective (as inferred in Table 19.3), but the cost of the energy saving is slightly above the threshold. On the other hand, this ECM is necessary for reasons of thermal comfort, both in winter (higher indoor mean radiant temperature of the inner side of the glazed façade) and summer (limitation of the indoor overheating, thanks to the installation of solar shadings).

19.4.4 The Cost-Optimal Refurbishment and Further Profitable ECMs: Application and Global Costs

Even if the main documents and international guidelines regarding building energy efficiency concern the investigations of ECMs for reducing the energy demand for space heating, space cooling, and production of domestic hot water, the energy efficiency in buildings should be addressed by acting on all levers connected to the energy consumption. To that end, there are many other issues that can be addressed, such as the energy demand for lighting and the integration of the energy supplied from the city grid with energy converted onsite by means of RESs. Therefore, according to the main topic of this chapter—that is, the conjugation of energy efficiency with the architectural respect paid to an ancient building and the implementation of renewable sources when these do not affect the building value—further EEMs have been taken into consideration. In particular:

All told, the following bulleted lists present a summary of the applied ECMs, specifying the investment costs. Moreover, for both buildings, new models have been built to simulate the energy savings achievable at the end of the refurbishments. Indeed, these last simulations combine all ECMs previously evaluated as feasible, so that the combined effect can be here evaluated.

Annually, by converting all energy demands in primary energy, by taking into consideration the Italian efficiency of the thermoelectric system (i.e., 0.46 Wh_EL/Wh_TH), the following evaluable outcomes have been calculated.

The monthly outcomes are shown in Fig. 19.11. Furthermore, because of the double role of public institutions (which can be exemplar in applying the European guidelines in matter of reduction of pollution, but also must be careful with respect to the use of public money), according to the cost optimality of energy renovation projects, the feasibility of the refurbishments is shown in Fig. 19.12.

In the calculation of the global costs, the application of Eq. (19.7) has been performed, by considering, for uniformity with Tables 19.2 and 19.3, a discounting factor R_d equal to 3% annually. According to the indication of the EU delegated regulation 244/2012 (EU Commission, 2012), the considered time horizon is 20 years. More in detail, Fig. 19.12 shows the main outcomes, in terms of DSP and NPV20 (Graphs A and C, respectively for Palazzo San Domenico and Appia Railway Station) and in terms of global costs (Graphs B and D). As it is easily understandable, the energy refurbishments satisfy all feasibility criteria. In particular, the investments can be repaid in 15 and 12 years for Palazzo San Domenico and Appia Railway Station respectively, while, for a period of 20 years, the global costs (by taking into account both investments and operational expenditures) are significantly lower for the refurbished buildings compared to the base cases.

With reference to Palazzo San Domenico, it should be underlined that all EEMs are strictly respectful of the historical value of the building.

19.4.5 Indoor Comfort Conditions

A last investigation analyzes, even if briefly, another important issue, and thus what happens in terms of indoor thermal comfort, as a consequence of the energy refurbishment of buildings.

Also in this case, as in the base cases, the buildings with mere refurbishment of the heating and cooling systems have been considered. Indeed, comparisons of the present buildings with the refurbished ones do not make sense, as the indoor conditions of the present edifices are not satisfactory because of the partial heating and cooling services that are currently available.

Fig. 19.13 shows, for significant environments, the operative temperatures inside Palazzo San Domenico (Graphs A and B) and for Appia Railway Station (Graphs C and D), before and after the renovations.

For Palazzo San Domenico, the replacement of the old lamps with LED systems plays a significant role in terms of the indoor conditions of the refurbished building. Indeed, in both the heating and cooling seasons, there is a lower radiant internal gain. In winter, the improved insulation of the roof compensates for this minor free contribution, so that the comfort conditions are allowed also in terms of mean radiant temperatures of the surfaces. Conversely, the lower radiant endogenous gains, in summer, allow for better comfort by keeping the mean radiant temperatures cool, not increased by the lamps. It should be noted that, from the point of view of the capability of fan coils (base case) and of DX units (VRF, refurbished buildings) in maintaining the set-points, both systems can perfectly allow the desired indoor air temperature.

With reference to the Appia Railway Station, of course the results in terms of indoor temperature and comfort have been calculated for the staircase. Indeed, none of the EEMs applied to the building (installation of heat recovery systems, adoption of condensing gas boiler, installation of PV systems on the roof) have effects on the indoor conditions, but are merely aimed at lowering the energy demand.

The only one applied ECM that affects the indoor microclimate is the replacement of the single-glazed windows of the staircase and the installation of low-emissive glasses, effective frames, and solar shadings. Therefore, a microclimatic study has been performed for this space. In detail, in Figs. 19.13C and D, the benefits of this ECM are immediately evident. Indeed, in Fig. 19.6F, the high energy losses (i.e., the low mean radiant temperature of the inner face of the glazed area of the staircase) are evident, and this is a great criticality of the present building. The new solutions for the glazed façade, as well as the installation of solar shading, allow a much lower energy loss during the space-heating period (i.e., higher surface temperatures and thus higher operative temperatures, also during the not-occupied periods; see Fig. 19.13C). At the same time, the shadings imply much lower solar gains during the summer period (i.e., much lower surface temperature, because of the minor heat gains; see Fig. 19.13D). Finally, the indoor operative temperatures are much better in both seasons. With reference to the other spaces within the Appia Railway Station, the improvement of the microclimate is not relevant compared to the base case (of course, the difference concerns the energy demands).