Thermal rehabilitation of buildings facades with exterior ... · Thermal rehabilitation of buildings facades with exterior insulation systems Extended Abstract 1 1. Introduction In

Thermal rehabilitation of buildings facades with exterior

insulation systems

Bruno André Pirão Freire

Extended Abstract

Supervisor: Prof. António Heleno Domingues Moret Rodrigues

June 2015

Thermal rehabilitation of buildings facades with exterior insulation systems

Extended Abstract

1

1. Introduction

In the early of the XXI century, residential and services buildings sectors were responsible for 40% of

final energy consumption in the European Union, which led to the introduction of legislation to ensure

that they gradually consume less energy. In that way, the European Commission published Directive

2002/91/EC [1] related to energy performance of buildings (EPBD - Energy Performance of Buildings

Directive), with the main objective to adopt: (i) a methodology of calculation of the integrated energy

performance of buildings; (ii) minimum requirements on the energy performance of new buildings and

large existing buildings that are subject to major renovation; (iii) energy certification of buildings; (iv) the

regular inspection of boilers and of air conditioning systems. In 2010, this directive was recast by

Directive 2010/31/EU (EPBD recast) [2], which aims to strengthen those previous provisions and

implement new measures to ensure the following objectives in 2020: 20% reduction in emissions of

greenhouse gas effect; increase by 20% the renewable energy production and; 20% increase in energy

efficiency. In addition to improve the objectives previously defined by Directive 2002/91/EC, this

reformulation introduced an approach for calculating cost-optimal levels of minimum requirements for

the energy performance of new and existing buildings that are present in the Commission Delegated

Regulation (EU) Nº244/2012 [3]. This approach is based on a comparative methodology related to

climatic conditions, investment costs, maintenance and operating costs (including energy costs and

savings, the category of building concerned, earnings from energy produced), where applicable, and

disposal costs, where applicable. As a result of reduction in the number of new buildings and the

expansion potential of the rehabilitation of existing buildings in Portugal [4], is intended to perform an

analysis of the performance of some external thermal insulation composite systems (ETICS), since they

have potential to improve the thermal and energy performance of existing buildings. This analysis will

be based on a case study building in Lisbon through dynamic simulation of its thermal and energy

behaviour, generated by EnergyPlus software, and subsequent application of European methodology

for calculating cost-optimal levels associated with each of the ETICS systems under study.

2. Case study definition

The case study is defined by a building in need of thermal rehabilitation and built before the first

regulation about building thermal performance characteristics (RCCTE) [5]. The chosen case study is

an entire floor of a residential building with 10 floors, built in 1967, with four apartments per floor and

four outer facades (Figure 1). This will allow a performance analysis according to the cardinal points

because each apartment is directed to each of the cardinal points (North, South, East and West). In

addition, there are two similar buildings in the adjacent plots (Figure 2), which allow the possibility of

repeat the building rehabilitation strategy. In this case, the building in study is located in Lisbon area,

more precisely in Olivais neighbourhood, and is integrated into winter climate zone I1 and summer

climate zone V2, according to the current regulation [6] (Figure 3). The energy performance analysis of

the chosen floor and apartments will be realized before thermal rehabilitation, preserving the original

exterior walls construction characteristics, and after thermal rehabilitation, which will be tested with

various ETICS solutions according to the different solar orientations.


Extended Abstract

2

2.1. Geometry

The chosen floor of the building has four apartments, each one with three bedrooms, called AP01-E

AP02-N, AP03-O and AP04-S, which solar orientations are East, North, West and South, respectively

(Figure 4). All apartments are symmetric and each one has 74.13m2 of floor area and a ceiling height of

2.8m. The opaque facade of each apartment occupies approximately 77% of outside area and the

remaining 23% are glazing.

Figure 4 - Floor plan and three-dimensional modeling of the case study floor.

2.2. Building elements characterization

About the building facade is assumed two facades solutions before the building thermal rehabilitation.

One of them is composed by the existing solution of double masonry brick wall with air gap between

them and without thermal insulation (SO1) and the other solution is composed by a single masonry brick

wall (SO2), which is a solution that exists in many buildings built before the first RCCTE. The present

study will focus on the performance of ETICS solutions in rehabilitation applied only to exterior walls,

since the remaining construction elements (glazing, interior walls, floors and ceilings) will maintain its

original constitution and will not be implemented any rehabilitation solution in these elements. In that

way, Table 1 shows the heat transfer coefficients of different construction elements that will be part of

the dynamic simulations in order to analyze the building energy performance.

Table 1 - Heat transfer coefficients of existent construction elements. Exterior walls

Interior walls Floors and

ceilings Glazing

SO1 SO2

U (W/m2.ºC) 1.09 1.39 1.75 2.41 5.74

Figure 1 - Building exterior perspective.

Figure 2 - Building location. Figure 3 - Winter and summer climate zoning for case study [6].

AP01-E AP03-O

AP04-S

AP02-N


Extended Abstract

3

2.3. Characterization of rehabilitation solutions with ETICS

The following simulations of thermal rehabilitation of facades with ETICS will show different types of

insulation applied to these systems such as expanded polystyrene (EPS), extruded polystyrene (XPS),

mineral wool (MW) and insulation cork board (ICB). These rehabilitation solutions will be applied with

thermal insulation thicknesses of 20, 40, 60, 80 and 100mm to each of the original solutions (SO1 and

SO2). Table 2 presents the heat transfer coefficients of each thermal rehabilitation solutions applied in

the original solutions.

Table 2 - Heat transfer coefficients of rehabilitation solutions with ETICS to each of original solutions.

3. Energy needs

The purpose of this section is to calculate nominal energy needs per m2 in heating and cooling seasons

to each of the original solutions and thermal rehabilitation with ETICS solutions. The calculation of these

energy needs is made by modeling the building floor chosen, with all the definitions described above,

and perform a dynamic simulation with EnergyPlus software. In that way, is intended to compare the

results of the original solutions SO1 and SO2 to respective rehabilitation solutions. The weather file used

for the dynamic simulation was the Lisbon weather data [7] and the heating season length was defined

in 5.3 months and the cooling season length in 4 months (June, July, August and September). Heating

and cooling set-points are assumed to be 18ºC and 25ºC, respectively and according to the thermal

regulation [6].

3.1. Usage patterns

For energy needs simulation, internal gains were defined by the number of occupants living daily in each

apartment, lighting and equipments. The current energy performance regulation for residential buildings

[6] establishes a permanent average value of 4W/m2 for internal gains without considering specific

usage patterns but, in this simulation, internal gains were calculated from a daily usage patterns for an

increase approach between the simulation and reality [8] (Figure 5). The average number of occupants

per m2, the average of annual energy consumption for lighting and equipments in residential buildings

are defined according to the survey Inquérito ao Consumo de Energia no Sector Doméstico 2010 [9].

For ventilation, it is assumed that takes place equally in all fractions and without mechanical systems.

The ventilation rate was determined through simplified criteria of previous regulation (RCCTE),

assuming that the case study has unrated windows/doors frames for air permeability, windows blind box

SO1

Exterior double

wall

Thick. (mm) 20 40 60 80 100 20 40 60 80 100 20 40 60 80 100 20 40 60 80 100

U (W/m2.ºC) 0.70 0.52 0.41 0.34 0.29 0.68 0.50 0.39 0.32 0.28 0.70 0.52 0.41 0.34 0.29 0.73 0.55 0.44 0.37 0.32

SO2

Exterior single

wall

Thick. (mm) 20 40 60 80 100 20 40 60 80 100 20 40 60 80 100 20 40 60 80 100

U (W/m2.ºC) 0.82 0.58 0.45 0.37 0.31 0.79 0.55 0.43 0.35 0.29 0.82 0.58 0.45 0.37 0.31 0.86 0.62 0.49 0.40 0.34

ETICS with expanded polystyrene ETICS with extruded polystyrene ETICS with mineral wool ETICS with insulation cork board

SO1 EPS SO1 XPS SO1 MW SO1 ICB

SO2 EPS SO2 XPS SO2 MW SO2 ICB


Extended Abstract

4

and the absence of air intake devices in the facade. Table 3 presents the usage patterns, lighting and

equipment power and the rate of air renewal.

Table 3 - Internal gains usage patterns and air

renewal rate [9].

Figure 5 - Internal gains usage patterns through

the day.

Heating and cooling equipments will also work only when the occupants are at home, which makes its

operation restricted to the schedule from 18h to 8h.

For the calculation of the energy needs for cooling season it is assumed the use of shading devices

(exterior shutters of plastic rulers) that are activated when the incident solar radiation on the glazing

exceeds 300W/m2, although this option is disabled for heating season.

3.2. Energy needs in heating season

Figure 6 presents the energy needs in kWh/m2 in heating season for each apartment, with the original

solution SO1 and respective rehabilitation solutions with ETICS.

Figure 6 - Energy needs for heating in all apartments for SO1 and rehabilitation solutions with ETICS.

The annual energy savings in relation to SO1 solution ranges, on average, between 11% and 25%, for

thicknesses of 20mm and 100mm respectively, and for the apartment with more energy needs in heating

Occupation (number of occupants) 3

Occupation period

Every day from 18h to 8h (activity period from

18h to 24h and from 7h to 8h; sleeping

period from 24h to 7h)

Total daily gain (Wh/m2) 51

Average power per hour (W/m2) 2.13

Lighting Every day from 18h to 24h

Consumption per hour (Wh) 149

Daily consumption per m2 (Wh/m

2) 8.35


Equipment

Every day 24 hours (usage pattern 1: from

24h to 7am; usage pattern 2: from 7h to

18h; usage pattern 3: from 18h to 24h)

Daily consumption per m2 (Wh/m

2) 46


Daily internal gains per m2 (Wh/m

2) 105

Average internal gains per hour (W/m2) 4.40

Hourly air renewal rate (Rph) 1.05

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Po

we

r (W

/m2)

Hours of the day (h)

Occupants Equipment Lighting

0

2

4

6

8

10

12

14

16

18

20

22

24

AP01-E AP02-N AP03-O AP04-S

En

erg

y n

ee

ds

(k

Wh

/m2)

Apartments

SO1

SO1EPS20

SO1EPS40

SO1EPS60

SO1EPS80

SO1EPS100

SO1XPS20

SO1XPS40

SO1XPS60

SO1XPS80

SO1XPS100

SO1MW20

SO1MW40

SO1MW60

SO1MW80

SO1MW100

SO1ICB20

SO1ICB40

SO1ICB60

SO1ICB80

SO1ICB100


Extended Abstract

5

season (AP02-N). For the apartment with lower energy needs in heating season (AP04-S), the annual

savings is located on average between 12% and 27% for thicknesses of 20mm and 100mm respectively.

With regard to the SO2 solution (Figure 7), energy savings for the apartment with more energy needs

in heating season (AP02-N) ranges on average between 14% and 29% to 20mm and 100mm

thicknesses respectively. For the apartment with lower energy needs in heating season (AP04-S),

annual savings are located on average between 16% and 32% for 20mm and 100mm thicknesses

respectively.

Figure 7 - Energy needs for heating in all apartments for SO2 and rehabilitation solutions with ETICS.

3.3. Energy needs in cooling season

Figures 8 and 9 presents energy needs for cooling season relative to SO1, SO2 and respective

rehabilitation solutions with ETICS. As can be seen, the largest energy savings in this season takes

place in AP01-E and AP04-S apartments, which have higher energy needs during this period. For the

other two apartments, AP02-N and AP03-O, the reduction in energy needs with rehabilitation solutions

is relatively low and there are no wide variations between energy needs of different rehabilitation

solutions with differents thicknesses. In these figures it is also concluded that rehabilitation solutions

with ETICS are less effective in decreasing energy needs in cooling season compared to heating season.

Figure 8 - Energy needs for cooling in all apartments for SO1 and rehabilitation solutions with ETICS.

0

2

4

6

8

10

12

14

16

18

20

22

24

26


En

erg

y n

ee

ds

(k

Wh

/m2)

Apartments

SO2

SO2EPS20

SO2EPS40

SO2EPS60

SO2EPS80

SO2EPS100

SO2XPS20

SO2XPS40

SO2XPS60

SO2XPS80

SO2XPS100

SO2MW20

SO2MW40

SO2MW60

SO2MW80

SO2MW100

SO2ICB20

SO2ICB40

SO2ICB60

SO2ICB80

SO2ICB100

0

1

2

3

4

5

6

7

8

9

10


En

erg

y n

ee

ds

(k

Wh

/m2)

Apartments

SO1

SO1EPS20

SO1EPS40

SO1EPS60

SO1EPS80

SO1EPS100

SO1XPS20

SO1XPS40

SO1XPS60

SO1XPS80

SO1XPS100

SO1MW20

SO1MW40

SO1MW60

SO1MW80

SO1MW100

SO1ICB20

SO1ICB40

SO1ICB60

SO1ICB80

SO1ICB100


Extended Abstract

6

Figure 9 – Energy needs for cooling in all apartments for SO2 and rehabilitation solutions with ETICS.

4. Cost-optimal analysis

As mentioned above, EPBD 2010 provides that Member States shall ensure implementations with the

minimum requirements related to energy performance in order to achieve cost-optimal levels [2], [3].

The optimal cost is obtained from the global costs associated with the improved energy performance

measures for a period of 30 years. The global cost of a rehabilitation solution is given by the sum of

construction costs, which take place in the year when project starts, with the deferred costs in time, for

a calculation period of 30 years, related to energy (heating and cooling) necessary to ensure the indoor

thermal comfort, and maintenance work to ensure the performance quality of the solution during the

period established. The global cost (𝐶𝑔) is obtained by the following expression [3]:

,

1

, )()( fd

i

iaIg ViRCCC

(1)

where means the calculation period; 𝐶𝐼 means initial investment cost for measure of energy efficiency;

𝑅𝑑(𝑖) means discount factor for year i; 𝑉𝑓,𝜏 means residual value of measure at the end of the calculation

period (discounted to the starting year 𝜏0) and 𝐶𝑎,𝑖 means annual cost during year i for measure of

energy efficiency as [3]:

𝐶𝑎,𝑖 = 𝐶𝑒,𝑖 + 𝐶𝑚,𝑖 (2)

where 𝐶𝑒,𝑖 means energy cost for year i and 𝐶𝑚,𝑖 means maintenance cost of rehabilitation solution for

year i. The discount factor 𝑅𝑑(𝑖) is obtained based on discount rate r, which is defined as 3%, and

according with the following expression [3]:

𝑅𝑑(𝑖) = (

1

1 + 𝑟/100)𝑖

(3)

where (𝑖) means the number of years from the starting períod.

0

1

2

3

4

5

6

7

8

9

10


En

erg

y n

ee

ds

(k

Wh

/m2)

Apartments

SO2

SO2EPS20

SO2EPS40

SO2EPS60

SO2EPS80

SO2EPS100

SO2XPS20

SO2XPS40

SO2XPS60

SO2XPS80

SO2XPS100

SO2MW20

SO2MW40

SO2MW60

SO2MW80

SO2MW100

SO2ICB20

SO2ICB40

SO2ICB60

SO2ICB80

SO2ICB100


Extended Abstract

7

To calculate the energy costs for a period of 30 years, were obtained the annual heating and cooling

energy needs for the case study and the different rehabilitation solutions applied (Table 2). It is possible

to calculate the final energy (annual) from the ratio between energy needs (from heating and cooling)

and energy efficiency EER/COP of HVAC equipments for heating and cooling. Assuming that all the

apartments in study have the same type of air conditioning system, corresponding to thermal production

units of air conditioning systems with efficiency class C, is obtained, for systems with split units,

multissplit and VRF, a minimum EER of 2.80 and a minimum COP of 3.20 [6]. From the calculation of

the annual final energy is obtained the primary energy through the conversion factor of energy used (2.5

in case of electricity). Then, the results were normalized by the floor area of the case study. The price

of electricity for the calculation was analyzed from a simple tariff of low voltage, higher than 3.45 kVA

and lower than 6.9 kVA, and the value used was 0.1497€/kWh based on reference prices of liberalized

electricity market published by ERSE for 2014 and for the tariff "EDP Comercial Casa" [10]. This price

was updated according to European Commission forecast for energy prices and respective interest rate

[11]. Maintenance costs used for each ETICS solutions correspond to a ten-year period costs according

to CYPE Gerador de Preços [12]. For construction costs were considered the cost of the material used

and his installation, for each rehabilitation measures adopted [13].

In Figures 10, 11 and 12 are presented cost-optimal graphs for different rehabilitation solutions with

ETICS compared to the original solutions SO1 and SO2. In each graph is indicated the insulation

thickness value considered optimum for each rehabilitation solution.

Figure 10 – Cost-optimal graphs for SO1 and rehabilitation solutions with ETICS, for the apartments

AP01-E and AP02-N.

SO1

SO1EPS40

SO1XPS40

SO1MW40

SO1ICB20

26

28

30

32

34

36

38

40

42

44

46

50 52 54 56 58 60 62 64 66

Glo

ba

l co

st

pe

r flo

or

are

a (

€/m

2)

Primary energy kWh/(m2.ano)

AP01-E

SO1 SO1EPS SO1XPS

SO1MW SO1ICB

SO1

SO1EPS60

SO1XPS40

SO1MW40

SO1ICB40

26

28

30

32

34

36

38

40

42

44

60 62 64 66 68 70 72 74 76 78 80

Glo

ba

l co

st

pe

r flo

or

are

a (

€/m

2)


AP02-N

SO1 SO1EPS SO1XPS

SO1MW SO1ICB


Extended Abstract

8

Figure 11 – Cost-optimal graphs for SO1 and rehabilitation solutions with ETICS, for the apartments

AP03-O and AP04-S.

Figure 12 - Cost-optimal graphs for SO2 and rehabilitation solutions with ETICS, for the apartments

AP01-E, AP02-N, AP03-O and AP04-S.

SO1SO1EPS40

SO1XPS40

SO1MW40

SO1ICB20

25

27

29

31

33

35

37

39

41

43

45

42 44 46 48 50 52 54 56 58

Glo

ba

l co

st

pe

r flo

or

are

a (

€/m

2)


AP03-O

SO1 SO1EPS SO1XPS

SO1MW SO1ICB

SO1

SO1EPS40

SO1XPS20

SO1MW20

SO1ICB20

22

25

28

31

34

37

40

43

46

35 40 45 50

Glo

ba

l co

st

pe

r flo

or

are

a (

€/m

2)

Primaty energy kWh/(m2.ano)

AP04-S

SO1 SO1EPS SO1XPS

SO1MW SO1ICB

SO2

SO2EPS40

SO2XPS40

SO2MW40

SO2ICB40

24

26

28

30

32

34

36

38

40

42

44

48 51 54 57 60 63 66 69 72

Glo

ba

l co

st

pe

r flo

or

are

a (

€/m

2)


AP01-E

SO2 SO2EPS SO2XPS

SO2MW SO2ICB

SO2

SO2EPS60

SO2XPS60

SO2MW40

SO2ICB40

24

26

28

30

32

34

36

38

40

42

60 62 64 66 68 70 72 74 76 78 80 82 84

Glo

ba

l co

st

pe

r flo

or

are

a (

€/m

2)


AP02-N

SO2 SO2EPS SO2XPS

SO2MW SO2ICB

SO2SO2EPS40

SO2XPS40

SO2MW40

SO2ICB40

24

26

28

30

32

34

36

38

40

42

44

42 44 46 48 50 52 54 56 58 60 62 64

Glo

ba

l co

st

pe

r flo

or

are

a (

€/m

2)


AP03-O

SO2 SO2EPS SO2XPS

SO2MW SO2ICB

SO2

SO2EPS40

SO2XPS40

SO2MW40

SO2ICB20

21

23

25

27

29

31

33

35

37

39

41

43

45

35 37 39 41 43 45 47 49 51 53 55

Glo

ba

l co

st

pe

r flo

or

are

a (

€/m

2)


AP04-S

SO2 SO2EPS SO2XPS

SO2MW SO2ICB


Extended Abstract

9

5. Conclusions

According to the cost-optimal graphics it is concluded that, for SO1 solution, only apartments oriented

to east and north (AP01-E and AP02-N) may benefit from savings, from a financial point of view, through

rehabilitation solutions with ETICS. In case of apartment AP01-E, only ETICS solution with EPS is below

the SO1 reference value with a cost-optimal corresponding to 40mm insulation thickness (SO1EPS40).

In AP02-N apartment, ETICS solutions with EPS, XPS and MW are those producing savings compared

to the original solution with the cost-optimal situated in 60mm thickness in case of EPS (SO1EPS60)

and 40mm thickness in case of XPS (SO1XPS40) and MW (SO1MW40). In the other apartments,

oriented to west and south (AP03-O and AP04-S), all presented rehabilitation solutions are above the

reference value for original solution SO1.

For SO2 solution, the conclusion is similar to SO1 solution where only apartments oriented to east and

north (AP01-E and AP02-N) benefit from rehabilitation ETICS solutions, establishing savings from a

financial point of view and for a period of 30 years. The difference between them is that in SO2 solution,

and for AP01-E apartment, rehabilitation solutions with EPS and XPS are beneficial and, for AP02-N

apartment, all rehabilitation solutions with ETICS analyzed (with EPS, XPS, MW and ICB) are below the

reference value of SO2 solution. In case of AP01-E apartment, the cost-optimal was obtained from

ETICS with EPS and XPS solutions with 40mm insulation thickness (SO2EPS40 and SO2XPS40). For

AP02-N apartment, cost-optimal was defined, in case of EPS and XPS with 60mm thickness

(SO2EPS60 and SO2XPS60) and for MW and ICB solutions was set to 40mm insulation thickness

(SO2MW40 and SO2ICB40). In the others apartments, AP03-O and AP04-S, none of the rehabilitation

solutions with ETICS obtained a value lower than the original solution SO2.

With these results it is concluded that rehabilitation solutions with ETICS systems applied to this

particular building are more effective in apartments with highest energy needs for heating, having this

heating season an important weight in calculation of primary energy. It is also expected that the

progressive increase of air conditioning systems efficiency and the reduction of reference comfort

temperature (from 20°C in the previous legislation to 18°C in the current regulation), give rise a reduction

of benefits from rehabilitation measures with ETICS, from a financial point of view, and may influence

the choice of the type of insulation to be implemented.

6. References

[1] Comissão Europeia, “Directiva 2002/91/CE do Parlamento Europeu e do Conselho de 16 de

Dezembro de 2002 relativa ao desempenho energético dos edifícios,” Jornal Oficial das

Comunidades Europeias, p. 7, 2002.

[2] Comissão Europeia, “Directiva 2010/31/UE do Parlamento Europeu e do Conselho de 19 de Maio

de 2010 relativa ao desempenho energético dos edifícios,” Jornal Oficial da União Europeia, p.

23, 2010.


Extended Abstract

10

[3] Comissão Europeia, “Regulamento Delegado (UE) N.º 244/2012 da Comissão de 16 de Janeiro

de 2012 que complementa a Diretiva 2010/31/UE do Parlamento Europeu e do Conselho,” Jornal

Oficial da União Europeia, p. 19, 2012.

[4] Instituto Nacional de Estatística, Estatísticas da Construção e Habitação 2010, Lisboa: Instituto

Nacional de Estatística, 2011, p. 93.

[5] Ministério das Obras Públicas, Transportes e Comunicações, “Decreto-Lei nº 40/90 de 6 de

Fevereiro, Regulamento das Características do Comportamento Térmico dos Edifícios, RCCTE,”

Diário da República - 1ª Série, p. 15, 1990.

[6] Ministério da Economia e do Emprego, “Decreto-Lei nº 118/2013 de 20 de Agosto de 2013,

Regulamento de Desempenho Energético dos Edifícios de Habitação, REH,” Diário da República

- 1ª Série, p. 18, 2013.

[7] INETI, “Lisbon weather file,” 2014. [Online]. Available:

http://apps1.eere.energy.gov/buildings/energyplus/cfm/weather_data3.cfm/region=6_europe_wm

o_region_6/country=PRT/cname=Portugal. [Acedido em 2 Junho 2014].

[8] N. Pereira, Energy-Efficient Retrofit of Residential Buildings, Lisbon 1960's - 70's case study,

Lisboa: Intituto Superior Técnico, 2012, pp. 252-257.

[9] INE e DGEG, Inquérito ao Consumo de Energia no Sector Doméstico 2010, Lisboa: Instituto

Nacional de Estatística e Direcção-Geral de Energia e Geologia, 2011, p. 117.

[10] INE; DGEG, “Inquérito ao Consumo de Energia no Sector Doméstico 2010,” Instituto Nacional de

Estatística e Direcção-Geral de Energia e Geologia, Lisboa, 2011.

[11] ERSE, Entidade Reguladora dos Serviços Energéticos, “Preços de referência no mercado

liberalizado de energia elétrica e gás natural em Portugal Continental,” Agosto 2014. [Online].

Available: http://www.erse.pt/pt/Simuladores/Documents/Pre%C3%A7osRef_BTN.pdf. [Acedido

em 20 Setembro 2014].

[12] European Commission, EU Energy, Transport and GHG Emissions, Trends to 2050, Reference

Scenario 2013, Luxembourg: Publications Office of the European Union, 2014, pp. 47-53.

[13] CYPE Ingenieros, S.A., “Gerador de preços,” 2014. [Online]. Available:

http://www.geradordeprecos.info/. [Acedido em 29 Setembro 2014].

[14] Saint-Gobain Weber Portugal, S.A., “Simulador de Cálculo,” 2014. [Online]. Available:

http://www.paredeseficientes.com/index.php. [Acedido em 23 Julho 2014].