Keywords: hotels, nZEB, neZEH, energy use, refurbishment
TEBE Research Group, SiTI,
Politecnico di Torino, Italy
Stefano Paolo Corgnati
Vice-president of REHVA,
TEBE Research Group, DENERG,
Politecnico di Torino, Italy
Project Officer at REHVA
Vice-president of REHVA,
Faculty of Civil Engineering,
Project Assistant at REHVA
The focus of the European project neZEH on hotels raised the question of how to define requirements for nearly Zero Energy Buildings when complex buildings are concerned. This paper presents the first steps made to enter this topic, including a review of the existing hotel buildings stock energy performances.
According to the UNWTO-UNEP study (2008)  tourism contributes around 5% to global CO2emissions, out of which hotels and other types of accommodation account for 1%.
This comparatively small footprint is nevertheless important in the EU strategies to achieve the 2020 goals, as proved by the projects dealing with the hospitality sector promoted by the IEE in the last years, such as HES and RELACS, and neZEH project which started in spring 2013.
The most recent goal to be achieved within the hotel sector goes beyond the generic increase in the energy efficiency and use of renewables: the neZEH project aims at retrofitting existing hotels to achieve the nearly zero energy level.
Among the several building uses, focusing on the existing building stock of the hotel sector could be an asset for leveraging the nearly Zero Energy Building (nZEB) 2020 goal because:
· hotels’ guests may replicate at home the architectural solutions they experienced in the hotel;
· energy consumption in hotels is usually higher than in residential buildings, providing more opportunities for consistent energy savings;
· as the hotel sector is highly competitive, it is very likely that the advantages gained by some hotels toward the nZEB goal will push other to imitation.
The neZEH project
Nearly Zero Energy Hotels (neZEH) is a 3-years long project supported by the Intelligent Energy Europe (IEE) program, started in April 2013. It involves a consortium of 7 European Countries (Croatia, France, Greece, Italy, Romania, Spain, Sweden) and 10 partners, among whom REHVA provides the technical expertise in the field of buildings energy performances.
The project aims at accelerating the refurbishment rate of existing buildings into nZEB in the hospitality sector and promoting the front runners. Particularly, neZEH focuses on the SME hotels, which represent the 90% of the European hospitality sector and are usually the most reluctant to commit to energy saving measures and to the use of renewable energies. In order to convince hotel owners to invest significantly in refitting their buildings, successful examples of existing neZEH will be showcased (Figure 1). The interested hoteliers will be supported in designing feasible and sustainable renovation projects: 14 pilot projects will be implemented in 7 Countries to prove the profitability of deep refurbishments achieving NZE hotels.
To achieve these goals, neZEH works within the legal framework of the nZEB implementation in each partner Country, tackling the main market barriers that prevent SME hotel owners from investing in major refurbishment projects.
Originally the project was supposed to use existing national legal requirements, but the delay in the transposition of the EU nZEB definition in most of the involved Countries, lead REHVA to face a new task: the definition of Country specific reference values using available benchmarks.
The outcomes of this preliminary study are shown in the following paragraphs.
Figure 1. One of neZEH project showcases: the zero energy Stadthalle Hotel in Vienna.
Actual energy use of existing hotels
To understand the relevance of the energy costs on the operational costs of a tourist accommodation building at the present stage, an overview of the available data on energy use of existing hotels is provided.
BPIE data hub
After its major study Europe’s Buildings under the Microscope (2011) , BPIE created a data hub for the energy performance of buildings. Refining the search for energy use of hotel buildings, relevant available data are listed for some European Member States by building age group. For this article the information extracted is per country as a maximum to minimum range of delivered energy use level set by the age groups values (Table 1).
Table 1. Max … min range of energy use for hotel buildings in some European Member States, extracted from the BPIE data hub.
Hotels and restaurants
1946 … 2004
350 … 217
1900 … 2002
430 … 290
1975 … 2005
397 … 292
1940 … 2010
185 … 140
1983 … 2011
296 … 220
1951 … 2006
545 … 190
Hotel Energy Solutions
The Hotel Energy Solutions (HES) project reported significant variations of energy use in facility types within the hotel sector. However, it concluded that regarding climatic conditions, overall energy use levels can be relatively constant (energy needs for cooling and heating balance out), but with significant differences in the necessary technologies to reduce energy use in different climate zones.
In addition, HES provided:
· average energy use levels according to available certification schemes for the energy performance of hotels (e.g. Accor, Nordic Swan, LowE, WWF/IBLF, Thermie) i.e.delivered energy use range 200–400 kWh/(m²∙a) with average energy use 305–330 kWh/(m²∙a);
· definition of five energy performance ratings, shown in Table 2.
Table 2. Hotels’ energy performance rating defined in the HES project.
Energy performance rating
195 … 280
280 … 355
355 … 450
Comparing the values inferred from BPIE data hub and from HES, a similar range of energy use in hotels is highlighted.
To determine Country specific values, data from ENTRANZE project were used. The project delivered an EU online data mapping tool including buildings’ energy uses updated at 2008 (the last year with available data not affected by the economic crisis). Data about the current situation of energy use in buildings in the European Countries involved in the project were given with an energy breakdown by energy source. In the context of neZEH, data for residential buildings (Table 3) were used.
Table 3. Energy use in residential buildings with energy breakdown by energy source for the Countries involved in the ENTRANZE project.
Residential Buildings Energy Consumption 2008 level
Residential Buildings Energy Breakdown by Energy Source
Consistently with the conclusions drawn by HES, which affirms that energy use levels can be relatively constant among hotels as far as energy needs for climatization are concerned, these were the functions considered to define the average energy use of hotels. These functions, here named “hosting function”, will be further specified in the paragraph The typical energy use of a hotel.
To use the data provided by ENTRANZE in the specific context of hotels, the energy needs for the hosting functions were considered similar to the residential buildings’ ones, with an additional contribution of energy for cooling and ventilation. While the extra ventilation-related energy use was constant, the relevance of the additional cooling load depended on the climate zone. With national primary energy factors, the primary energy use of existing hotels at 2008 level was calculated, as shown in Table 4.
Table 4. Energy use in hotels with details of the increased contribution for ventilation and cooling with respect to values for residential buildings.
Ventilation Delivered Energy
Cooling Delivered Energy
Ventilation Primary Energy
Cooling primary energy
Hotels Hosting Function
Definition of benchmarks for neZEH
One of the main expected outputs of the neZEH project is the setting up of hotels renovation projects in line with the definition of nZEB. Moreover, it is important to demonstrate to hoteliers that achieving the nZEB target is cost-effective by providing existing examples of neZEH.
Both these tasks entail a practical definition of neZEH.
The typical energy use of a hotel
The first issue to be faced is how to define in a hotel the “typical use of the building”, upon which the energy performance of the building is based (EPBD, Article 2) .
Different hotels may offer different facilities, which entails a wide gap in the energy needs even among buildings with the same general use classification. Hotels can have similar energy consumption related to the their hosting function, typically related to energy use in guestrooms, but diverse energy needs when the offered facilities are concerned.
The approach to the problem chosen by the authors was to compare the reference values for primary energy dealing only with the hotels’ energy use for the hosting functions.
The selection criteria for specifying the hosting functions was suggested by the EPBD (2002) , affirming that the energy performance of a building derives from the climatic indoor environmental quality targets set for it. The energy performance of a building for its standard use (heating, cooling, ventilation, hot water, lighting) must refer to the standard indoor environmental conditions, which in a hotel are the comfort conditions required for guests and workers, as recommended in EN15251 . With these premises, the standard zones of a hotel to be considered among the hosting functions were selected: guests’ rooms; reception hall; offices; bar and restaurant; meeting rooms.
Reference values for the definition of a neZEH
The second key aspect was the definition of proper reference values for Primary Energy and integration of Renewable Energy Sources.
To define neZEH, available definitions of nZEB were grouped according to the geographical division proposed by the Ecofys report 2013 , in order to consider regional disparities regarding, among others, climatic and economic differences. The selected Countries representing Zones 1 (Mediterranean Europe), 2 (Eastern Central Europe), 3 (Western Central Europe) and 4 (Northern Europe) were respectively Italy, Slovakia, France and Estonia.
The final reference values are presented in Table 5.
Table 5. Summary of the requirements for nearly zero energy hotels in Europe.
domestic hot water,
It is worth noting that, at this stage, the available definitions exploited are not referred to the achievement of the cost-optimal level, despite its fundamental role for obtaining a concrete reduction on buildings’ energy consumptions – especially in retrofit actions.
From primary energy values of existing hotels (Table 4) and neZEH values of Table 5, the Country specific reduction percentages were calculated. For a coherent comparison between the current and the nearly-zero energy consumption, the benchmarks set for neZEH were increased by the contribution of appliances (final values are shown in Table 6). The appliances impact was quantified as an extra energy use of 7 kWh/m² weighted by the national primary energy factors. With these adjustments, the reduction percentages, displayed in Table 6, ranged between 67 to 81% of the primary energy of existing hotels, with an average decrease of 74.5%, meaning that primary energy use of existing building stock need to be reduced by factor of 4 in average (varied between 3–5).
Table 6. Reduction percentages of primary energy for existing buildings to calculate national benchmarks for hotels.
Hotels hosting function
Hotels hosting function
neZEH benchmark (with appliances added)
The first steps within the neZEH project allowed the authors to have an overview of the current situation of the European hotels’ energy consumptions and of how ambitious are the targets set for reaching the nearly zero energy level.
Some available national consistent nZEB definitions allowed to determine benchmark values for nearly zero hotels in four climate zones. Comparison with existing buildings showed that the primary energy use of existing hotels is in average by factor 4 higher relative to determine neZEH benchmark values.
Being the national implementation of the nZEB definition late at the national level, the neZEH project had to face the hard task of defining its own benchmarks, by exploiting the information available so far. Therefore, despite the rigorous methodology followed to define the neZEH benchmarks, some critical considerations are needed:
· the existing definitions exploited refer to new buildings;
· the figures are now settled as fixed figures, which do not take into account the cost-optimality approach.
Considering the cost-optimal level of energy performance for refurbished buildings will necessarily lead to an increase of these benchmarks. While new buildings can nowadays be easily designed as zero energy buildings, refurbishment actions have to face many technical constraints which may not allow to reach the target.
 UNWTO-UNEP, Climate Change and Tourism: Responding to Global Challenges, 2008.
 BPIE, Europe’s Buildings under the Microscope, 2011.
 Directive 2002/91/CE of the European Parliament and the Council of 16 December 2002 on the energy performance of buildings.
 Directive 2010/31/EU of the European Parliament and the Council of 19 May 2010 on the energy performance of buildings (recast).
 EN 15251 (2008). Criteria for Indoor Environment including thermal, indoor air quality, light and noise. European Standard.
 ECOFYS, Towards nearly zero-energy buildings - Definition of common principles under the EPBD. Final report, February 2013.
 The Hotel Energy Solutions is an UNWTO-initiated project in collaboration with a team of United Nations and EU leading agencies in Tourism and Energy. The project delivers information, technical support & training to help Small and Medium Enterprises (SMEs) in the tourism and accommodation sector across the EU 27 to increase their energy efficiency and renewable energy usage. http://hotelenergysolutions.net/en
The RELACS (REnewabLe energy for tourist ACcomodation buildingS) is a IEE project - launched at the end of May 2010 in Modena - involving partners from 10 countries. It aims to involve and motivate a significant number of accommodations throughout Europe (at least 60) in implementing renewable energy technologies as well as energy efficiency measures on their buildings.http://www.relacs.eu/home.php
The objective of the ENTRANZE project is to assist policy makers in developing integrated, effective and efficient policy packages achieving a fast and strong penetration of NZEB and RES-H/C focusing on the refurbishment of existing buildings in line with the EPBD and the RED. http://www.entranze.eu/