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Upgrading the Fabric of
Athenian Hotels
Konstantinos Koletsos
Building Fabric 2014-2015
MSc in Environmental Design of Buildings
Welsh School of Architecture, Cardiff University
Page 2
Table of contents
5
Map of the world containing the average U-values required for windows for high indoor
thermal comfort without radiators (ΔT external surface/room temperature = 4.2 K) . It
is created based on the data from the EOSWEB climate database [NASA 2009]
Source: (International Passive House Association 2014)
Introduction ……………………………………………………………………………………………………………..3
Part 1 - Ranking of environmental aspects………………………………………………………………..4-8
1. Decision criteria
1.1 Thermal comfort
1.2 Visual comfort
1.3 Sound comfort
2. Main aspect
Part 2 - Thermal insulation & noise control……..……………………………………………………...9-15
3. Optimization of guest room
4. Standard envelopes in Greece
5. Optimal Layer Distribution
6. Types of insulation material
7. Windows efficiency
7.1 Type of frame
7.2 Glazing
Conclusion ……………………………………………………………………………………………………….……16
References …………………………………………………………………………………………………………….17-19
Appendices …………………………………………………………………………………………………………...20-22
Page 3
Introduction
Hotels present a paradox to be resolved. They rely on the conservation of natural
resources to run their business and, at the same time, deplete them by being major
energy consumers. Carbon-intensive accommodation and inefficient operations, as
attested by a number of researchers (Farrou et al. 2012; Bohdanowicz and Martinac
2007; Dascalaki and Balaras 2004), appear responsible for considerably charging
today’s environmental problems1
. The European statutory environment for energy and
carbon efficiency, alongside an increasing demand for lower operational costs in the
competitive hospitality sector, urge for upgrading existing facilities (Karagiorgas et al.
2006, p.200).
This paper is, in the first part, hierarchizing alternative environmental aspects in
retrofitting the fabric of ageing Athenian hotels. This is done by investigating their
applicability to local climate, energy demand and comfort variables in the guest room
zone. Energy consumption in hotels and their potential for sustainable development
are, after all, directly related to the presence of guests (Beccali et al. 2009, p.86). City
hotels, operating year-round, are selected. In the second part, a main aspect is more
thoroughly reviewed. Existing technologies are compared and the most appropriate to
the building type and regional characteristics is proposed.
1
The estimated annual hotel-based CO2 emissions are 160-200Kg/m2 of room floor area (Hotel Energy
Solutions 2011a, p.2).
Figure 1: Southwest view of typical two and three star hotels
in Athens built in the 1970s. Picture taken in a mild January
afternoon.
Page 4
Part 1 - Ranking of environmental aspects
1. Decision criteria
Energy is primarily used for space conditioning in Greek hotels, as shown below.
Potential energy savings in Euro-
pean hotels also indicate the im-
portance of heating and cooling in
terms of minimizing the life cycle
cost of their facilities.
Table 1: Estimated savings per energy end-use. ( Source: European Commission 1994 , cited in Dascala-
ki and Balaras 2004, p.1091)
Alternative environmental strategies are thus evaluated and ranked primarily accord-
ing to their heating and cooling capacity and consequently on their contribution to vis-
ual and sound comfort. The final ranking decision rests on the principle that the “guest
experience” upon which hotels build their brand and customer loyalty should not be
compromised by energy efficiency alone (Quaintance et al. 2010, p.5).
1.1 Thermal comfort
An initial step to designing an energy efficient building is to understand the local cli-
mate. Climate Consultant was used to determine the hours of the year the climate of
Athens is within the comfort ranges for a particular strategy. Athens is a Csa climatic
region, i.e. a temperate climate with hot and dry summers, according to Köppen-Geiger
classification (Gialamas 2011).
ASHRAE standard 55-2004 using the Predicted Mean Vote (PMV) was used in setting
the thermal comfort criteria. An adaptive approach would not be appropriate in hotel
design as any occupant adjustments in response to outdoor temperature changes
would occur gradually (CIBSE Guide A 2006, p.16) over a period slightly exceeded by
the 9-night average stay of guests in Greek hotels (Rerres et al. 2013, p.18).
Heating Cooling Lighting DHW
15-20% 5-30% 7-60% 40-70%
Figure 1: Energy breakdown in a Greek
hotel. (Source: Hotel Energy Solutions
2011b, p.19)
Page 5
Part 1 - Ranking of environmental aspects
A residential building analysis was selected since guestrooms offer the same adaptive
options to indoor conditions as residences. The balance heating temperature of the
Internal Heat Gains zone (IHGs) was set at 17.1°C to adjust to the 0,50 utilization factor
assigned to hotel guestrooms in Greece.2
Large city center terrain was selected for the
natural ventilation cooling zone.
Although it is reported that “rented rooms remain unoccupied for approximately 60 -
65 per cent during the day” (Hotel Energy Solutions 2011a, p.4), no available data
related exclusively to city center hotels and their specific operations were found. Two
bioclimatic charts were thus produced for combinations of activity and clothing based
on hourly temperature, relative humidity and wind speed data. In the first combination,
from 8am to midnight, light sedentary activity at 1,1met and light clothing factors of
0,8Clo for the winter and 0,5Clo for the summer were selected. In the nighttime
combination, from midnight to 8am, activity was set at 0,9met to account for sleeping
and clothing insulation at 0,5Clo for both seasons.
Listed high mass passive strategies apply only in part to the retrofit context of our
analysis since existing fabrics in most Greek hotels consist of both uninsulated (Farrou
et al. 2012, p.557) and low inertia elements, such as cavity walls made up of lightweight
perforated bricks (Stazi et al. 2014, p.5). Unless the enclosure is insulated first, there is
a risk of unwanted, stored heat being flushed into the room overnight during a hot
period deteriorating the existing conditions (Hampton 2010, p.3).
2
A utilization factor of 0,75 is assumed in residences for setting the IHGs zone balance temperature. For
hotel bedrooms it is 0,50 (Τ.Ο.ΤΕ.Ε. 20701-1; Technical Chamber of Greece 2010, p.35). This figure
agrees with the 55% annual average occupancy ratio of Greek hotels (Association of Greek Tourism
Enterprises 2010, p.22).
Figure 2: Psychrometric Chart for day-
time schedule. (Source: Climate Con-
sultant)
The tables of effective passive
strategies of both charts
showed that the climate in
Athens is in the comfort range
for 1.098 hours a year, while
2.115 hours account for inter-
nal heat gains. For 3.586 hours
additional heating and cooling
is needed, all passive strategies
considered.
Page 6
Part 1 - Ranking of environmental aspects
Moreover, decreasing diurnal swings due to the heat island effect, not counted in the
weather data generated from a suburban station, and the higher number of predicted
tropical nights with temperatures above 20o
C (Zerefos et al. 2011, pp.61-62) curtail high
mass strategies from producing viable cooling comfort.
Passive strategies for heating, such as direct solar gains for low mass, and passive
cooling through natural ventilation and evaporative means account for 2.498 hours in
total.
According to the number of hours that relevant strategies meet the comfort criteria
over a year, for both daytime and nighttime schedules, their ranking is the following:
Figure 4: Ranking of strategies in
terms of thermal comfort hours
Figure 3: Psychrometric Chart for
nighttime schedule. (Source:
Climate Consultant)
Page 7
Part 1 - Ranking of environmental aspects
1.2 Visual comfort
Good daylight levels in guest rooms is the desired outcome in weighing the daylighting
strategy. “In conventional buildings [with window to wall ratios significantly lower than
the ones expected in hotel guest rooms3
] daylight penetrates about 4 to 6m from the
external walls” (European Commission 1994, p.6). The guest room zone in a five star
Greek hotel has a minimum depth of 5,3m according to the local codes (Hellenic
Republic Directive No 43 2002, p.517) hence during sunshine hours most of the room
could be adequately lit from natural daylighting.
In particular, a west facing wall in Athens receives mean annual radiation of 180W/m2
,
i.e. approximately 18.000 lux of illumination, as seen in figure 5.
That could bring 3,6 times more natural light on average within the room than the 250
lux recommended for hotel guest rooms (Androutsopoulos 2012, p.29) at an assumed
daylight factor of 5% for a predominantly day-lit appearance (McMullan 2012, p.165).
Although overshadowing is anticipated in the city center, we could reasonably argue
that natural illumination would suffice in most planning schemes without resorting to
electric lighting, saved task and bathroom illumination.
3
Doors (opening height > 2,0m) are often employed in guest rooms for allowing access to balconies as
required in hotel ratings
Figure 5: Incident radiation on a west-
ern vertical surface in Athens with
35% ground reflectance. Source: Cli-
mate Consultant.
Page 8
Part 1 - Ranking of environmental aspects
1.3 Sound comfort
Hotels are customer responsive businesses. Noise control in facilities located in dense
urban environments with high traffic noise is a chief concern in attaining comfort.
Quietness was reported among the basic reasons for selecting a hotel in Greece,
according to a study conducted by the (Association of Greek Tourism Enterprises 2010,
p.16).
Road traffic noise according to another survey conducted in the city of Rhodes is the
primary cause of tourist annoyance (Frantzeskakis et al.1999, cited in Vogiatzis et al.
[no date] p.42). The majority of tourists who were questioned expressed a negative
viewpoint on the quality of sleep due to exterior noise levels. Although the role of
acoustics may not be directly related to energy consumption, its importance in the
appreciation of the facilities is crucial and should be addressed at an early stage of the
planning process, as “...4 in 5 people would not return to a hotel if they found it
noisy.” (Vincent 1992 cited in Vogiatzis et al. [no date] p.44)
2. Main environmental aspect
Based on the previous analysis, the main aspects that should be prioritized in a design
strategy for retrofitting Athenian hotels are thermal insulation and noise control.
Prioritizing thermal insulation is also responding to a voluntary assessment of hotel
facilities by eco-certifications, such as ELTAS (EU flower), addressed to a European level.
It has been argued (Butler 2012 cited in Zhang et al. 2014, p.6) that such schemes
improve the operational efficiency of hotels and, therefore, they could be integrated
early on in the design framework. According to EU Flower’s mandatory criteria, only
window insulation among the above listed aspects relates directly to the specificity of
the building fabric (European Commission 2009 cited in Hotel Energy Solutions, 2011b,
p. 13).
Moisturecontrol
Thermal mass & storage
Daylighting
Solarcontrol
Natural ventilation &infiltration
Passiveheating & cooling
Noise control
Thermal insulation
Illustration ofrelativeimportance
Figure 6: Final ranking of aspects
Page 9
Part 2 - Thermal Insulation & Noise Control
Thermal insulation is further reviewed in this part with respect to the building type
requirements, the existing conditions, its contribution to thermal and sound comfort
and, finally, its energy savings potential. The review focuses on the following two
elements, as they pertain to all guest room floors:
1. Exterior wall assemblies
2. Windows efficiency
3. Optimization of guest room area
“Planning the guest room floor (Ronstedt and Frey 2014, p.106) is crucial in hotel
business as every error multiplies itself by the number of identically stacked floor
plans.” The objective is to accommodate as many guest rooms per floor as possible by
reducing room sizes to the acceptable standards set by state regulations for each hotel
category.4
In Athens the majority of existing city hotels are two
and three star hotels5
in which the minimum double
bed guest room floor area is 11m2
or 12m2
for 2,80m
and 3,00m minimum bay widths respectively in a two
star hotel and 13m2
or 14m2
for 3,00m and 3,20m
bay widths in three star hotels (Hellenic Republic
Directive 43 2002, p.517). An additional interior
insulation layer at 10cm thickness of a conventional
insulant for a wall U-value=0,3 Wm-2
K-1
(INZEB 2014,
p.14) placed on the exterior and the adjoining side
walls to avoid thermal bridges would detract 5,6% of
usable floor making this measure functionally
problematic (Approved Document L2B 2014, p.22).
4
“For the hotelier five additional rooms per floor mean 23% increase in rentable rooms at equal
building cubature” as illustrated in the example presented by (Ronstedt and Frey 2014, p.106).
5
418 hotels from a total of 692 located in Athens according to a 2003 census (Source: Hellenic Chamber
of Hotels)
Figure 7: typical guest room layout of 3,2m bay width with mo-
bility features (U.S Department of Justice 2010, para. Transient
lodging guest room floor plans and related text).
Page 10
Part 2 - Thermal Insulation & Noise Control
4. Standard envelopes in Greece
Most Greek hotels were constructed in the 1970s and 1980s (Dascalaki and Balaras
2004, p.1092) with little or no insulation and poor performing glazing (see Appendix 2)
thus causing a great percentage of summer and winter discomfort. Typical construction
of this period is characterized by the following elements:
· Reinforced concrete bearing frame
· Cavity walls with perforated clay bricks
· Single or double pane, aluminum framed windows without thermal block. Low
air tightness
· Flat concrete roof slabs usually finished with bitumen covering. Comparable
construction to that of storey floors
It will be necessary to significantly change the thermal and sound performance of these
enclosures if they are to comply with minimum current standards (see Appendix 3).
Window R’w=31dB. Min requirement
of sound protection from exterior
noise LAeq,h=35dB for a standard level
of comfort in guest rooms (Greek
building regulations, article 12)
Figure 8: Typical wall section of uninsu-
lated buildings in Greece built in the
1970s. (Source of U-values : Laskos et
al. 2010, pp. 8-9)
Page 11
Part 2 - Thermal Insulation & Noise Control
5. Optimal layer distribution
It has been argued that “the best thermal performance of the building fabric can be
achieved by placing the insulating material to the inside for climatic regions where
winter heating is dominant and to the outside where cooling is dominant” (Al-Homoud
2005, p.354). Recent studies, though, on optimally upgrading the thermal performance
of cavity brick walls in a typical Mediterranean climate, with two distinct seasons, show
that exterior insulation outperforms the interior in terms of achieving less temperature
variations, better interior surface temperatures and lower energy consumption year-
round (Stazi et al. 2013; Kolaitis, et al. 2013).
Specifically, in the study conducted by (Stazi et al. 2013), the effects of insulation layer
distribution on a brick cavity wall performance were compared under identical roof,
floor and window conditions and under similar occupancy schedules to the intermittent
use of the heating and cooling systems expected in a hotel’s guest room zone for the
following cases:
1. Unfilled brick cavity wall, as built
2. Added internal insulation, 9cm Expanded Polystyrene (EPS)
3. Cavity insulation, 9cm Polyurethane Foam
4. Added external insulation, 9cm EPS
5. Added ventilated external insulation, 9cm EPS. Air channel closed in winter and
ventilated in summer.
The study concluded (Stazi
et al. 2013, p.441) that a
considerable thickness of
thermal insulation in cavity
walls is beneficial for both
winter and summer condi-
tions, while the ventilated
external insulation scenario
proved better performing
year-round.
Moreover, it outperformed traditional exterior insulation attached to existing walls in
terms of avoiding overheating during summertime, while the additional air space of
closed vents resulted in lower thermal transmittance in the winter.
6
External insulation outperformed the internal configuration by 8% in total energy requirements (Kolaitis
et al. 2013, p. 131).
Figure 9: Internal surface temperatures for uninsulated, externally insulat-
ed, and externally insulated ventilated system (Stazi et al. 2013, p. 438).
Page 12
Part 2 - Thermal Insulation & Noise Control
The benefits of a dynamically ventilated exterior insulation layer, sealed in wintertime
and open in summer are additionally illustrated in a 2014 study on the behavior of
traditional envelopes in Mediterranean climates (Stazi et al. 2014). The research team
has further developed “...a patented pre - assembled system with air vents made of
insulating material...” (Stazi et al. 2014, p.4) that claims to surpass the installation
complexity and poor winter thermal performance of the existing technology.
Still, ventilated façades in general need detailed design and skilled execution as any
future repairs are difficult and cost-intensive. As (Lemieux and Totten 2010, para. Cavity
Wall) point out, possible corrosion of steel members and interior mold growth remain
undetected for a period of years before the problem is exposed in a location accessible
for repair.
Figure 10: Schematic representation of a ventilated exterior wall
insulation (Source: Lemieux and Totten 2010)
Page 13
Part 2 - Thermal Insulation & Noise Control
6. Types of insulation material
Moisture tolerance, as indicated in figure 10, and low thermal conductivity are the main
properties in the evaluation of insulants placed in ventilated walls.
In Mediterranean climates, an average thickness of 15cm7
of traditional insulation
materials with thermal conductivities between 0,030 to 0,040W/(mK) suffice to meet
the low heat transfer criteria of passive buildings (Bank of Greece 2010, p.307). State-of
-the-art products, such as Vacuum Insulated Panels (VIPs) and Aerogels, which could be
beneficial in lowering the logistics and technical skill cost of big thickness insulation up
to 50cm required in northern climates (Jelle 2011, p.2533), would not offer a distinctive
advantage to most of today’s retrofitting projects in Athens.
Among traditional insulation materials, the least thermal conductivity under increasing
moisture content is provided by Polyurethane (PUR). Still, its hazardous toxicity when
burnt, would not make it the safest choice. The second best choice would be Extruded
Polystyrene (XPS) or Expanded Polystyrene (EPS). Both have a low thermal conductivity
while offering excellent and good moisture resistances respectively (Jelle 2011, pp.
2551-2552; Al-Homoud 2005, p.362).
In noisy urban sites, the option of
Elastic Expanded Polystyrene (EEPS)
should also be considered as an
alternative. EEPS can improve noise
control in solid and cavity walls by a
frequency range average of 10dB, in
contrast to standard EPS, XPS and
PUR rigid boards that may even
deteriorate the sound performance
when directly fixed to the wall
surface (Chené and Baux 2012, p.11;
Wetzel and Vogdt 2007, p.44).
7
Indicative insulation thickness in scenarios for minimizing energy demand in Greek buildings as a
response to climate change (Bank of Greece 2010).
Figure 11: Typical peak hours in the streets of
Athens. Part of a hotel’s view is shown on the
left.
Page 14
Part 2 - Thermal Insulation & Noise Control
7. Windows efficiency
As discussed, it is common for hotels to provide large apertures to offer access to
balconies and exterior views. The thermal efficiency and noise control of windows,
therefore, should be a priority in achieving an overall high performance of the building
fabric. A window U-value between 1,20 and 1,60W/(m2
K) would be required in Greece
for a high thermal comfort throughout the year without relying on mechanical services
(International Passive House Association 2014) and a capacity to reduce 35dB of
exterior noise level.
If we were to keep the sizes and orientation of the openings unchanged, the upgrading
should be guided by the following parameters:
· Selection of a frame with UFrame ≤ 1,60W/(m2
K) and a small area factor to
decrease heat losses.
· Glazing with Ug ≤ 1,60W/(m2
K). Small g-value to reduce the anticipated higher
cooling load due to climate change (Bank of Greece 2010, pp. 92-93). High light
transmission to enhance quality of views.
· Airtight sealing of the perimeter joints to eliminate installation thermal and
sound bridges.
·
7.1 Type of frame
Hinged windows should be preferred over sliding ones, as they generally have lower
infiltration rates (U.S.DOE 2012a, Energy efficient windows, para. 19) and, therefore,
better thermal and sound performance. Aluminum frames with a thermal break or
insulated fiberglass frames are maintenance free while providing low U-values (U.S.
DOE 2012b, Window types). Narrow, deep profiles could minimize the area factor.
7.2 Glazing
Replacement of existing single pane glazing with double or triple, low-e glazing could
result in substantial energy savings. On east, and particularly on west elevations that
receive up to 900W/m2
solar radiation in the summer afternoons (see figure 4), triple
glazing with a low g-value of approximately 40% should be selected to avoid
overheating. On south elevations, where traditional shading solutions are foreseen,
heat absorbing glazing could be beneficial depending on site specific conditions. Better
sound performance is accomplished by simply selecting panes at different thicknesses
with a wider air space between them (Efficient Windows CollaborativeTM
2014, para.
Emerging Technologies-Glass; McMullan 2012, p.221).
Page 15
Part 2 - Thermal Insulation & Noise Control
Figure 10: Glazing
comparison (Source:
International Passive
House Association 2014)
Vacuum insulated glass, one of today’s lower heat transfer solutions for glazing, could
be appropriate for the climate of Athens as diurnal swings are below 35◦
C, but the
spacers used to stabilize the panes against wind pressure could negatively affect the
views from hotel windows (Efficient Windows CollaborativeTM
2014, para. Emerging
Technologies-Glass).
Page 16
Conclusion
Existing Athenian hotels could be substantially upgraded by adopting the following
measures on their fabrics:
1. Add a dynamically ventilated exterior insulation layer of EEPS at an optimum
thickness to bring the heat transfer coefficient of existing walls to passive standards and
improve their thermal and sound performance.
2. Replace updated windows with energy efficient ones with dual or triple, low-e and
low heat transmission, panes at different thicknesses.
Such measures would be an initial step towards carbon efficient facilities that comply
with the most rigorous of today’s practices while offering the best possible
environments to their guests.
Zero energy balance hotel, Stadhalle, Wien
(Source: https://www.hotelstadthalle.at/city-hotel-vienna)
Page 17
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[Online]. Available at: http://www.ada.gov/regs2010/2010ADAStandards/
Guidance2010ADAstandards.htm [Accessed: 22 December 2014]
Vogiatzis, C. Psychas, K. Chaikali, S. [no date]. Environmental noise as a design parameter in
urban tourist areas in Greece. A social, technical & legal approach. Acoustique & Techniques
no 24, pp. 41-49.
Wetzel, C. and Vogdt, F.U. 2007. Improving the Quality of Existing Urban Building Envelopes:
Facades and Roofs. IOS Press under the imprint Delft University Press
Zerefos, C. Repapis, C. et al. 2011. The climate of Eastern Mediterranean and Greece: Past, pre-
sent and future. Environmental, Fiscal and Social Consequences of Climate Change in Greece.
[in Greek]. Bank of Greece. [Online]. Available at: www.bankofgreece.gr/BogEkdoseis/
Πληρης_Εκθεση.pdf [Accessed: 27 November 2014]
Zhang, J.J. Joglekar, N. Verma, R. Heineke, J. 2014. Exploring the relationship between eco-
certifications and resource efficiency in U.S. hotels. Cornell Hospitality Report Vol. 14, No. 7
(March 2014).
Page 20
Appendices
1
Source: (Farrou et al. 2012, p. 557)
2
Values assigned to the climatic zone of Athens by KENAK (2010). Regulation for
energy performance of buildings and technical guidelines of the Technical Chamber of
Greece.
Uw = 0,60 W/(m2
K), max heat transfer coefficient for external walls in contact with
outside air.
UF = 3,00 W/(m2
K), max heat transfer coefficient for windows and exterior doors.
Source: (Laskos et al. 2010, pp. 8-9)
3
Improvement and deterioration of the sound insulation of an existing external wall by
fitting ETICS (+)=improvement, (-)=deterioration
Case study: Single shell construction of existing sound insulation of Rw=54dB
Page 21
Appendices
Source: (Wetzel and Vogdt 2007, p. 44)
4
EEPS
MW
EPS
XPS & PUR
Concrete 15cm
Source: (Chené and Baux 2012, p.10)
Rendering
g<10Kg/m2
Rendering
g>10Kg/m2
Bonded PS ETICS -2 dB -1 dB
Bonded PS ETICS with more elastic PS 0 dB +1 dB
Bonded and dowelled PS ETICS -1 dB -2 dB
Bonded and dowelled MF ETICS, MF 50mm -4 dB +4 dB
Bonded and dowelled MF ETICS, MF 100mm -2 dB +2 dB
PS ETICS with rail mounting + 2dB + 2dB
Page 22
Appendices
5
Μεταβολές του αριθμού ημερών με ισχυρές ανάγκες για ψύξη μεταξύ
(α) 2021-205 0 και 1961-1990, (β) 2071-2100 και 1961-1990

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Building Fabric 2014 2015_K.Koletsos

  • 1. Upgrading the Fabric of Athenian Hotels Konstantinos Koletsos Building Fabric 2014-2015 MSc in Environmental Design of Buildings Welsh School of Architecture, Cardiff University
  • 2. Page 2 Table of contents 5 Map of the world containing the average U-values required for windows for high indoor thermal comfort without radiators (ΔT external surface/room temperature = 4.2 K) . It is created based on the data from the EOSWEB climate database [NASA 2009] Source: (International Passive House Association 2014) Introduction ……………………………………………………………………………………………………………..3 Part 1 - Ranking of environmental aspects………………………………………………………………..4-8 1. Decision criteria 1.1 Thermal comfort 1.2 Visual comfort 1.3 Sound comfort 2. Main aspect Part 2 - Thermal insulation & noise control……..……………………………………………………...9-15 3. Optimization of guest room 4. Standard envelopes in Greece 5. Optimal Layer Distribution 6. Types of insulation material 7. Windows efficiency 7.1 Type of frame 7.2 Glazing Conclusion ……………………………………………………………………………………………………….……16 References …………………………………………………………………………………………………………….17-19 Appendices …………………………………………………………………………………………………………...20-22
  • 3. Page 3 Introduction Hotels present a paradox to be resolved. They rely on the conservation of natural resources to run their business and, at the same time, deplete them by being major energy consumers. Carbon-intensive accommodation and inefficient operations, as attested by a number of researchers (Farrou et al. 2012; Bohdanowicz and Martinac 2007; Dascalaki and Balaras 2004), appear responsible for considerably charging today’s environmental problems1 . The European statutory environment for energy and carbon efficiency, alongside an increasing demand for lower operational costs in the competitive hospitality sector, urge for upgrading existing facilities (Karagiorgas et al. 2006, p.200). This paper is, in the first part, hierarchizing alternative environmental aspects in retrofitting the fabric of ageing Athenian hotels. This is done by investigating their applicability to local climate, energy demand and comfort variables in the guest room zone. Energy consumption in hotels and their potential for sustainable development are, after all, directly related to the presence of guests (Beccali et al. 2009, p.86). City hotels, operating year-round, are selected. In the second part, a main aspect is more thoroughly reviewed. Existing technologies are compared and the most appropriate to the building type and regional characteristics is proposed. 1 The estimated annual hotel-based CO2 emissions are 160-200Kg/m2 of room floor area (Hotel Energy Solutions 2011a, p.2). Figure 1: Southwest view of typical two and three star hotels in Athens built in the 1970s. Picture taken in a mild January afternoon.
  • 4. Page 4 Part 1 - Ranking of environmental aspects 1. Decision criteria Energy is primarily used for space conditioning in Greek hotels, as shown below. Potential energy savings in Euro- pean hotels also indicate the im- portance of heating and cooling in terms of minimizing the life cycle cost of their facilities. Table 1: Estimated savings per energy end-use. ( Source: European Commission 1994 , cited in Dascala- ki and Balaras 2004, p.1091) Alternative environmental strategies are thus evaluated and ranked primarily accord- ing to their heating and cooling capacity and consequently on their contribution to vis- ual and sound comfort. The final ranking decision rests on the principle that the “guest experience” upon which hotels build their brand and customer loyalty should not be compromised by energy efficiency alone (Quaintance et al. 2010, p.5). 1.1 Thermal comfort An initial step to designing an energy efficient building is to understand the local cli- mate. Climate Consultant was used to determine the hours of the year the climate of Athens is within the comfort ranges for a particular strategy. Athens is a Csa climatic region, i.e. a temperate climate with hot and dry summers, according to Köppen-Geiger classification (Gialamas 2011). ASHRAE standard 55-2004 using the Predicted Mean Vote (PMV) was used in setting the thermal comfort criteria. An adaptive approach would not be appropriate in hotel design as any occupant adjustments in response to outdoor temperature changes would occur gradually (CIBSE Guide A 2006, p.16) over a period slightly exceeded by the 9-night average stay of guests in Greek hotels (Rerres et al. 2013, p.18). Heating Cooling Lighting DHW 15-20% 5-30% 7-60% 40-70% Figure 1: Energy breakdown in a Greek hotel. (Source: Hotel Energy Solutions 2011b, p.19)
  • 5. Page 5 Part 1 - Ranking of environmental aspects A residential building analysis was selected since guestrooms offer the same adaptive options to indoor conditions as residences. The balance heating temperature of the Internal Heat Gains zone (IHGs) was set at 17.1°C to adjust to the 0,50 utilization factor assigned to hotel guestrooms in Greece.2 Large city center terrain was selected for the natural ventilation cooling zone. Although it is reported that “rented rooms remain unoccupied for approximately 60 - 65 per cent during the day” (Hotel Energy Solutions 2011a, p.4), no available data related exclusively to city center hotels and their specific operations were found. Two bioclimatic charts were thus produced for combinations of activity and clothing based on hourly temperature, relative humidity and wind speed data. In the first combination, from 8am to midnight, light sedentary activity at 1,1met and light clothing factors of 0,8Clo for the winter and 0,5Clo for the summer were selected. In the nighttime combination, from midnight to 8am, activity was set at 0,9met to account for sleeping and clothing insulation at 0,5Clo for both seasons. Listed high mass passive strategies apply only in part to the retrofit context of our analysis since existing fabrics in most Greek hotels consist of both uninsulated (Farrou et al. 2012, p.557) and low inertia elements, such as cavity walls made up of lightweight perforated bricks (Stazi et al. 2014, p.5). Unless the enclosure is insulated first, there is a risk of unwanted, stored heat being flushed into the room overnight during a hot period deteriorating the existing conditions (Hampton 2010, p.3). 2 A utilization factor of 0,75 is assumed in residences for setting the IHGs zone balance temperature. For hotel bedrooms it is 0,50 (Τ.Ο.ΤΕ.Ε. 20701-1; Technical Chamber of Greece 2010, p.35). This figure agrees with the 55% annual average occupancy ratio of Greek hotels (Association of Greek Tourism Enterprises 2010, p.22). Figure 2: Psychrometric Chart for day- time schedule. (Source: Climate Con- sultant) The tables of effective passive strategies of both charts showed that the climate in Athens is in the comfort range for 1.098 hours a year, while 2.115 hours account for inter- nal heat gains. For 3.586 hours additional heating and cooling is needed, all passive strategies considered.
  • 6. Page 6 Part 1 - Ranking of environmental aspects Moreover, decreasing diurnal swings due to the heat island effect, not counted in the weather data generated from a suburban station, and the higher number of predicted tropical nights with temperatures above 20o C (Zerefos et al. 2011, pp.61-62) curtail high mass strategies from producing viable cooling comfort. Passive strategies for heating, such as direct solar gains for low mass, and passive cooling through natural ventilation and evaporative means account for 2.498 hours in total. According to the number of hours that relevant strategies meet the comfort criteria over a year, for both daytime and nighttime schedules, their ranking is the following: Figure 4: Ranking of strategies in terms of thermal comfort hours Figure 3: Psychrometric Chart for nighttime schedule. (Source: Climate Consultant)
  • 7. Page 7 Part 1 - Ranking of environmental aspects 1.2 Visual comfort Good daylight levels in guest rooms is the desired outcome in weighing the daylighting strategy. “In conventional buildings [with window to wall ratios significantly lower than the ones expected in hotel guest rooms3 ] daylight penetrates about 4 to 6m from the external walls” (European Commission 1994, p.6). The guest room zone in a five star Greek hotel has a minimum depth of 5,3m according to the local codes (Hellenic Republic Directive No 43 2002, p.517) hence during sunshine hours most of the room could be adequately lit from natural daylighting. In particular, a west facing wall in Athens receives mean annual radiation of 180W/m2 , i.e. approximately 18.000 lux of illumination, as seen in figure 5. That could bring 3,6 times more natural light on average within the room than the 250 lux recommended for hotel guest rooms (Androutsopoulos 2012, p.29) at an assumed daylight factor of 5% for a predominantly day-lit appearance (McMullan 2012, p.165). Although overshadowing is anticipated in the city center, we could reasonably argue that natural illumination would suffice in most planning schemes without resorting to electric lighting, saved task and bathroom illumination. 3 Doors (opening height > 2,0m) are often employed in guest rooms for allowing access to balconies as required in hotel ratings Figure 5: Incident radiation on a west- ern vertical surface in Athens with 35% ground reflectance. Source: Cli- mate Consultant.
  • 8. Page 8 Part 1 - Ranking of environmental aspects 1.3 Sound comfort Hotels are customer responsive businesses. Noise control in facilities located in dense urban environments with high traffic noise is a chief concern in attaining comfort. Quietness was reported among the basic reasons for selecting a hotel in Greece, according to a study conducted by the (Association of Greek Tourism Enterprises 2010, p.16). Road traffic noise according to another survey conducted in the city of Rhodes is the primary cause of tourist annoyance (Frantzeskakis et al.1999, cited in Vogiatzis et al. [no date] p.42). The majority of tourists who were questioned expressed a negative viewpoint on the quality of sleep due to exterior noise levels. Although the role of acoustics may not be directly related to energy consumption, its importance in the appreciation of the facilities is crucial and should be addressed at an early stage of the planning process, as “...4 in 5 people would not return to a hotel if they found it noisy.” (Vincent 1992 cited in Vogiatzis et al. [no date] p.44) 2. Main environmental aspect Based on the previous analysis, the main aspects that should be prioritized in a design strategy for retrofitting Athenian hotels are thermal insulation and noise control. Prioritizing thermal insulation is also responding to a voluntary assessment of hotel facilities by eco-certifications, such as ELTAS (EU flower), addressed to a European level. It has been argued (Butler 2012 cited in Zhang et al. 2014, p.6) that such schemes improve the operational efficiency of hotels and, therefore, they could be integrated early on in the design framework. According to EU Flower’s mandatory criteria, only window insulation among the above listed aspects relates directly to the specificity of the building fabric (European Commission 2009 cited in Hotel Energy Solutions, 2011b, p. 13). Moisturecontrol Thermal mass & storage Daylighting Solarcontrol Natural ventilation &infiltration Passiveheating & cooling Noise control Thermal insulation Illustration ofrelativeimportance Figure 6: Final ranking of aspects
  • 9. Page 9 Part 2 - Thermal Insulation & Noise Control Thermal insulation is further reviewed in this part with respect to the building type requirements, the existing conditions, its contribution to thermal and sound comfort and, finally, its energy savings potential. The review focuses on the following two elements, as they pertain to all guest room floors: 1. Exterior wall assemblies 2. Windows efficiency 3. Optimization of guest room area “Planning the guest room floor (Ronstedt and Frey 2014, p.106) is crucial in hotel business as every error multiplies itself by the number of identically stacked floor plans.” The objective is to accommodate as many guest rooms per floor as possible by reducing room sizes to the acceptable standards set by state regulations for each hotel category.4 In Athens the majority of existing city hotels are two and three star hotels5 in which the minimum double bed guest room floor area is 11m2 or 12m2 for 2,80m and 3,00m minimum bay widths respectively in a two star hotel and 13m2 or 14m2 for 3,00m and 3,20m bay widths in three star hotels (Hellenic Republic Directive 43 2002, p.517). An additional interior insulation layer at 10cm thickness of a conventional insulant for a wall U-value=0,3 Wm-2 K-1 (INZEB 2014, p.14) placed on the exterior and the adjoining side walls to avoid thermal bridges would detract 5,6% of usable floor making this measure functionally problematic (Approved Document L2B 2014, p.22). 4 “For the hotelier five additional rooms per floor mean 23% increase in rentable rooms at equal building cubature” as illustrated in the example presented by (Ronstedt and Frey 2014, p.106). 5 418 hotels from a total of 692 located in Athens according to a 2003 census (Source: Hellenic Chamber of Hotels) Figure 7: typical guest room layout of 3,2m bay width with mo- bility features (U.S Department of Justice 2010, para. Transient lodging guest room floor plans and related text).
  • 10. Page 10 Part 2 - Thermal Insulation & Noise Control 4. Standard envelopes in Greece Most Greek hotels were constructed in the 1970s and 1980s (Dascalaki and Balaras 2004, p.1092) with little or no insulation and poor performing glazing (see Appendix 2) thus causing a great percentage of summer and winter discomfort. Typical construction of this period is characterized by the following elements: · Reinforced concrete bearing frame · Cavity walls with perforated clay bricks · Single or double pane, aluminum framed windows without thermal block. Low air tightness · Flat concrete roof slabs usually finished with bitumen covering. Comparable construction to that of storey floors It will be necessary to significantly change the thermal and sound performance of these enclosures if they are to comply with minimum current standards (see Appendix 3). Window R’w=31dB. Min requirement of sound protection from exterior noise LAeq,h=35dB for a standard level of comfort in guest rooms (Greek building regulations, article 12) Figure 8: Typical wall section of uninsu- lated buildings in Greece built in the 1970s. (Source of U-values : Laskos et al. 2010, pp. 8-9)
  • 11. Page 11 Part 2 - Thermal Insulation & Noise Control 5. Optimal layer distribution It has been argued that “the best thermal performance of the building fabric can be achieved by placing the insulating material to the inside for climatic regions where winter heating is dominant and to the outside where cooling is dominant” (Al-Homoud 2005, p.354). Recent studies, though, on optimally upgrading the thermal performance of cavity brick walls in a typical Mediterranean climate, with two distinct seasons, show that exterior insulation outperforms the interior in terms of achieving less temperature variations, better interior surface temperatures and lower energy consumption year- round (Stazi et al. 2013; Kolaitis, et al. 2013). Specifically, in the study conducted by (Stazi et al. 2013), the effects of insulation layer distribution on a brick cavity wall performance were compared under identical roof, floor and window conditions and under similar occupancy schedules to the intermittent use of the heating and cooling systems expected in a hotel’s guest room zone for the following cases: 1. Unfilled brick cavity wall, as built 2. Added internal insulation, 9cm Expanded Polystyrene (EPS) 3. Cavity insulation, 9cm Polyurethane Foam 4. Added external insulation, 9cm EPS 5. Added ventilated external insulation, 9cm EPS. Air channel closed in winter and ventilated in summer. The study concluded (Stazi et al. 2013, p.441) that a considerable thickness of thermal insulation in cavity walls is beneficial for both winter and summer condi- tions, while the ventilated external insulation scenario proved better performing year-round. Moreover, it outperformed traditional exterior insulation attached to existing walls in terms of avoiding overheating during summertime, while the additional air space of closed vents resulted in lower thermal transmittance in the winter. 6 External insulation outperformed the internal configuration by 8% in total energy requirements (Kolaitis et al. 2013, p. 131). Figure 9: Internal surface temperatures for uninsulated, externally insulat- ed, and externally insulated ventilated system (Stazi et al. 2013, p. 438).
  • 12. Page 12 Part 2 - Thermal Insulation & Noise Control The benefits of a dynamically ventilated exterior insulation layer, sealed in wintertime and open in summer are additionally illustrated in a 2014 study on the behavior of traditional envelopes in Mediterranean climates (Stazi et al. 2014). The research team has further developed “...a patented pre - assembled system with air vents made of insulating material...” (Stazi et al. 2014, p.4) that claims to surpass the installation complexity and poor winter thermal performance of the existing technology. Still, ventilated façades in general need detailed design and skilled execution as any future repairs are difficult and cost-intensive. As (Lemieux and Totten 2010, para. Cavity Wall) point out, possible corrosion of steel members and interior mold growth remain undetected for a period of years before the problem is exposed in a location accessible for repair. Figure 10: Schematic representation of a ventilated exterior wall insulation (Source: Lemieux and Totten 2010)
  • 13. Page 13 Part 2 - Thermal Insulation & Noise Control 6. Types of insulation material Moisture tolerance, as indicated in figure 10, and low thermal conductivity are the main properties in the evaluation of insulants placed in ventilated walls. In Mediterranean climates, an average thickness of 15cm7 of traditional insulation materials with thermal conductivities between 0,030 to 0,040W/(mK) suffice to meet the low heat transfer criteria of passive buildings (Bank of Greece 2010, p.307). State-of -the-art products, such as Vacuum Insulated Panels (VIPs) and Aerogels, which could be beneficial in lowering the logistics and technical skill cost of big thickness insulation up to 50cm required in northern climates (Jelle 2011, p.2533), would not offer a distinctive advantage to most of today’s retrofitting projects in Athens. Among traditional insulation materials, the least thermal conductivity under increasing moisture content is provided by Polyurethane (PUR). Still, its hazardous toxicity when burnt, would not make it the safest choice. The second best choice would be Extruded Polystyrene (XPS) or Expanded Polystyrene (EPS). Both have a low thermal conductivity while offering excellent and good moisture resistances respectively (Jelle 2011, pp. 2551-2552; Al-Homoud 2005, p.362). In noisy urban sites, the option of Elastic Expanded Polystyrene (EEPS) should also be considered as an alternative. EEPS can improve noise control in solid and cavity walls by a frequency range average of 10dB, in contrast to standard EPS, XPS and PUR rigid boards that may even deteriorate the sound performance when directly fixed to the wall surface (Chené and Baux 2012, p.11; Wetzel and Vogdt 2007, p.44). 7 Indicative insulation thickness in scenarios for minimizing energy demand in Greek buildings as a response to climate change (Bank of Greece 2010). Figure 11: Typical peak hours in the streets of Athens. Part of a hotel’s view is shown on the left.
  • 14. Page 14 Part 2 - Thermal Insulation & Noise Control 7. Windows efficiency As discussed, it is common for hotels to provide large apertures to offer access to balconies and exterior views. The thermal efficiency and noise control of windows, therefore, should be a priority in achieving an overall high performance of the building fabric. A window U-value between 1,20 and 1,60W/(m2 K) would be required in Greece for a high thermal comfort throughout the year without relying on mechanical services (International Passive House Association 2014) and a capacity to reduce 35dB of exterior noise level. If we were to keep the sizes and orientation of the openings unchanged, the upgrading should be guided by the following parameters: · Selection of a frame with UFrame ≤ 1,60W/(m2 K) and a small area factor to decrease heat losses. · Glazing with Ug ≤ 1,60W/(m2 K). Small g-value to reduce the anticipated higher cooling load due to climate change (Bank of Greece 2010, pp. 92-93). High light transmission to enhance quality of views. · Airtight sealing of the perimeter joints to eliminate installation thermal and sound bridges. · 7.1 Type of frame Hinged windows should be preferred over sliding ones, as they generally have lower infiltration rates (U.S.DOE 2012a, Energy efficient windows, para. 19) and, therefore, better thermal and sound performance. Aluminum frames with a thermal break or insulated fiberglass frames are maintenance free while providing low U-values (U.S. DOE 2012b, Window types). Narrow, deep profiles could minimize the area factor. 7.2 Glazing Replacement of existing single pane glazing with double or triple, low-e glazing could result in substantial energy savings. On east, and particularly on west elevations that receive up to 900W/m2 solar radiation in the summer afternoons (see figure 4), triple glazing with a low g-value of approximately 40% should be selected to avoid overheating. On south elevations, where traditional shading solutions are foreseen, heat absorbing glazing could be beneficial depending on site specific conditions. Better sound performance is accomplished by simply selecting panes at different thicknesses with a wider air space between them (Efficient Windows CollaborativeTM 2014, para. Emerging Technologies-Glass; McMullan 2012, p.221).
  • 15. Page 15 Part 2 - Thermal Insulation & Noise Control Figure 10: Glazing comparison (Source: International Passive House Association 2014) Vacuum insulated glass, one of today’s lower heat transfer solutions for glazing, could be appropriate for the climate of Athens as diurnal swings are below 35◦ C, but the spacers used to stabilize the panes against wind pressure could negatively affect the views from hotel windows (Efficient Windows CollaborativeTM 2014, para. Emerging Technologies-Glass).
  • 16. Page 16 Conclusion Existing Athenian hotels could be substantially upgraded by adopting the following measures on their fabrics: 1. Add a dynamically ventilated exterior insulation layer of EEPS at an optimum thickness to bring the heat transfer coefficient of existing walls to passive standards and improve their thermal and sound performance. 2. Replace updated windows with energy efficient ones with dual or triple, low-e and low heat transmission, panes at different thicknesses. Such measures would be an initial step towards carbon efficient facilities that comply with the most rigorous of today’s practices while offering the best possible environments to their guests. Zero energy balance hotel, Stadhalle, Wien (Source: https://www.hotelstadthalle.at/city-hotel-vienna)
  • 17. Page 17 References Androutsopoulos, A., Aravantinos, D., et al. 2012. T.Ο.ΤΕ.Ε. 20701-1/2010. Detailed national requirements of parameters for calculating the energy performance of buildings and issuing the energy performance certificate [in Greek]. 2nd ed. Athens, Greece. TEE, Technical Chamber of Greece. Ministry of Environment, Energy and Climate Change-YPEKA-Special Secretariat for Environmental Inspectorate and Energy. Special Ministry of Energy Inspectorate. Approved Document L2B 2014: Conservation of fuel and power in existing buildings other than dwellings. Building Regulations 2010 (2010/2214). Welsh Government. Association of Greek Tourism Enterprises 2010. Study for upgrading old hotel units. [in Greek]. [Online]. Available at: http://sete.gr/GR/VIVLIOThIKI [Accessed: 20 November 2014] Beccali, M. La Gennusa, M. Lo Coco, L. Rizzo, G. 2009. An empirical approach for ranking environmental and energy saving measures in the hotel sector. Renewable Energy 34, pp. 82- 90. Bohdanowicz, P. and Martinac, I. 2007. Determinants and benchmarking of resource consumption in hotels—Case study of Hilton International and Scandic in Europe. Energy and Buildings 39, pp. 82-95 Chené, J.B. and Baux, P. 2012. Thermique, acoustique, ventilation: Les vrais faux amis. Regards croisés entre un acoustician at un thermicien. [in French]. Conference proceedings: Concilier isolation thermique, confort acoustique et qualité de l'air intérieur : nouveautés techniques et réglementaires. Strasbourg, 15 November 2012 . [Online] Available at: http://www.bruit.fr/nos -services-aux-acteurs-du-bruit/colloques-et-journees-techniques/colloques-et-journees- techniques-les-archives/concilier-isolation-thermique-confort-acoustique-et-qualite-de-l-air- interieur-nouveaut.html#ancre_pdf [Accessed: 10 January 2015) CIBSE Guide A: Environmental Design. 7th edition 2006. [Online] Licensed copy from CIS: Cardiffuni, Cardiff University. [Accessed: 12 January 2015] Dascalaki, E. and Balaras, C.A. 2004. XENIOS—A methodology for assessing refurbishment scenarios and the potential of application of RES and RUE in hotels. Energy and Buildings 36, pp. 1091-1105. Efficient Windows CollaborativeTM 2014. Window Technologies. [Online]. Available at: http:// www.efficientwindows.org/adv_glass.php [Accessed: 22 December 2014] European Commission 1994. Daylighting in buildings. The European Commission Directorate- General for Energy (DGXVII). A Thermie Program Action. [Online]. Available at: http:// erg.ucd.ie/UCDERG/publications.html [Accessed: 16 December 2014] INZEB 2014. Renovation workshop results. [in Greek]. Green Building Expo 22 November 2014, Athens Greece. [Online] Available at: http://inzeb.org/renovation-workshop [Accessed: 18 January 2015] Farrou, I. Kolokotroni, M. Santamouris, M. 2012. A method for energy classification of hotels: A case-study of Greece. Energy and Buildings 55, pp. 553-562.
  • 18. Page 18 References Gialamas, I. 2011. Climate Classification of Greece in Köppen-Geiger. [in Greek]. [Online]. Available from: <http://www.meteoclub.gr/themata/egkyklopaideia/2618-klimatiki-katataksi- elladas> [Accessed: 17 January 2012]. Hampton, A. 2010. Thermal mass and insulation for temperate climates. [Online]. Environment Design Guide. Australian Institute of Architects. Available at: http:// environmentdesignguide.com.au/pages//content/recent-papers/edg-65-ah--thermal-mass-and -insulation-for-temperate-climates.php [Accessed: 15 December 2014] Hellenic Republic Directive 43 2002. Εφημερίς της κυβερνήσεως της Ελληνικής Δημοκρατίας. ΦΕΚ Αρ. Φύλλου 43. 7 Μαρτίου 2002. (Technical specifications and categorization of hotels). [in Greek] Hotel Energy Solutions 2011a. Analysis on energy use by European hotels: Online survey and desk research. Hotel Energy Solutions Project Publications. [Online]. Available at: http://hotelenergysolutions.net/content/hotel-energy-solutions-publications-overview [Accessed: 5 December 2014] Hotel Energy Solutions 2011b. Energy efficiency and renewable energy applications in the hotel sector. Hotel Energy Solutions Project Publications. [Online]. Available at: http://hotelenergysolutions.net/content/hotel-energy-solutions-publications-overview [Accessed: 1 December 2014] International Passive House Association 2014. Required U-values for Passive House windows. [Online]. Passivhaus Institut. Available at: http://www.passipedia.org/planning/ thermal_protection/windows/requirements_for_windows/required_u- values_for_passive_house_windows [Accessed: 22 December 2014] Jelle, B.P. 2011. Traditional, state-of-the-art and future thermal building insulation materials and solutions – properties, requirements and possibilities. Energy and Buildings 43, pp.2549– 2563. Karagiorgas, M. Tsoutsos, T. et al. 2006. HOTRES: Renewable energies in the hotels. An extensive technical tool for the hotel industry. Renewable & Sustainable Energy Reviews 10, pp. 198-224 Kolaitis, D.I. Malliotakis, E. Kontogeorgos, D.A. Mandilaras, I. Katsourinis, D.I. Founti, M.A. 2013. Comparative assessment of internal and external thermal insulation systems for energy efficient retrofitting of residential buildings, Energy and Buildings 64, pp. 123–131. Lemieux, D.J. and Totten, P.E. 2010. Building Envelope Design Guide – Wall systems. [Online] National institute of Building Sciences. Available at: http://www.wbdg.org/design/ env_wall.php#details [Accessed: 15 December 2014] McMullan, R. 2012. Environmental Science in Building. Palgrave Macmillan Ronstedt, M. and Frey, T. 2014. Construction and Design Manual, Hotel Buildings. Dom Publishers
  • 19. Page 19 References Stazi, F. Bonfigli, C. Tomassoni, E. Perna, C.Di. Munafo, P. 2014. The effect of high thermal insu- lation on high thermal mass: Is the dynamic behaviour of traditional envelopes in Mediterrane- an climates still possible? Energy and Buildings 88, pp.367-383. Stazi, F. Vegliςa, A. Pernab, C.Di. Munafςa, P. 2013. Experimental comparison between 3 differ- ent traditional wall constructions and dynamic simulations to identify optimal thermal insula- tion strategies. Energy and Buildings 60, pp. 429–441. Quaintance, D.W. Susskind, A.M. Farrell, A. 2010. Sustaining the right balance. Dispelling myths about green initiatives for hospitality and gaming. [Online]. Webcast sponsored by SAS and the Center for Hospitality Research at Cornell University’s School of Hotel Administration. Originally broadcast in March 2010. Available at: https://www.hotelschool.cornell.edu/research/chr/ [Accessed: 25 November 2014] Rerres, K.E. Christidou, A. et al. 2013. Developments in tourism and basic indicators of Greek hotels for 2012. [in Greek]. Research Institute For Tourism and Hellenic Chamber of Hotels. [Online]. Available at: http://www.grhotels.gr/GR/xee/ITEP/Pages/statistics.aspx [Accessed: 19 January 2015] U.S. Department of Energy 2012. Energy-Efficient windows. [Online]. Available at: http:// energy.gov/energysaver/articles/energy-efficient-windows [Accessed: 22 December 2014] U.S. Department of Justice 2010. Guidance on the 2010 ADA standards for accessible design. [Online]. Available at: http://www.ada.gov/regs2010/2010ADAStandards/ Guidance2010ADAstandards.htm [Accessed: 22 December 2014] Vogiatzis, C. Psychas, K. Chaikali, S. [no date]. Environmental noise as a design parameter in urban tourist areas in Greece. A social, technical & legal approach. Acoustique & Techniques no 24, pp. 41-49. Wetzel, C. and Vogdt, F.U. 2007. Improving the Quality of Existing Urban Building Envelopes: Facades and Roofs. IOS Press under the imprint Delft University Press Zerefos, C. Repapis, C. et al. 2011. The climate of Eastern Mediterranean and Greece: Past, pre- sent and future. Environmental, Fiscal and Social Consequences of Climate Change in Greece. [in Greek]. Bank of Greece. [Online]. Available at: www.bankofgreece.gr/BogEkdoseis/ Πληρης_Εκθεση.pdf [Accessed: 27 November 2014] Zhang, J.J. Joglekar, N. Verma, R. Heineke, J. 2014. Exploring the relationship between eco- certifications and resource efficiency in U.S. hotels. Cornell Hospitality Report Vol. 14, No. 7 (March 2014).
  • 20. Page 20 Appendices 1 Source: (Farrou et al. 2012, p. 557) 2 Values assigned to the climatic zone of Athens by KENAK (2010). Regulation for energy performance of buildings and technical guidelines of the Technical Chamber of Greece. Uw = 0,60 W/(m2 K), max heat transfer coefficient for external walls in contact with outside air. UF = 3,00 W/(m2 K), max heat transfer coefficient for windows and exterior doors. Source: (Laskos et al. 2010, pp. 8-9) 3 Improvement and deterioration of the sound insulation of an existing external wall by fitting ETICS (+)=improvement, (-)=deterioration Case study: Single shell construction of existing sound insulation of Rw=54dB
  • 21. Page 21 Appendices Source: (Wetzel and Vogdt 2007, p. 44) 4 EEPS MW EPS XPS & PUR Concrete 15cm Source: (Chené and Baux 2012, p.10) Rendering g<10Kg/m2 Rendering g>10Kg/m2 Bonded PS ETICS -2 dB -1 dB Bonded PS ETICS with more elastic PS 0 dB +1 dB Bonded and dowelled PS ETICS -1 dB -2 dB Bonded and dowelled MF ETICS, MF 50mm -4 dB +4 dB Bonded and dowelled MF ETICS, MF 100mm -2 dB +2 dB PS ETICS with rail mounting + 2dB + 2dB
  • 22. Page 22 Appendices 5 Μεταβολές του αριθμού ημερών με ισχυρές ανάγκες για ψύξη μεταξύ (α) 2021-205 0 και 1961-1990, (β) 2071-2100 και 1961-1990