5. TABLE OF CONTENTS
PART A – EUROPEAN SCENARIO 4.3 Conventional values 17
1. SUMMARY OF EUROPEAN DIRECTIVES ABOUT 5. APPLICABLE BEST PRACTICES 18
ENERGY EFFICIENCY IN BUILDINGS 5 5.1 Envelope performance 18
1.1 Directive 2002/91/EC on the energy performance 5.2 Renewable energy systems 18
of buildings (EPBD) 5 5.3 Energy efficient systems 19
1.1.1 Objective 5 5.4 Certification 19
1.1.2 Deadline for adoption 5
1.1.3 Energy performance of buildings 5 6. SOME EXAMPLES OF BEST PRACTICES 20
1.1.4 Methodology of calculation of the energy performance 6 Best Practices Example in France 20
1.1.5 Energy performance certificate 6 Best Practices Example in Italy 21
1.2 Directive 1992/42/EEC on efficiency requirements for Best Practices Example in Poland 23
new hot-water boilers fired with liquid or gaseous fuels 6 Best Practice Example in Spain 25
1.2.1 Objective 6 Best Practice Example in Romania 26
1.2.2 Efficiency requirements 6 Best practices example in Austria 28
1.3 Other Directives 7 Best Practices Example in Germany 30
2. OVERVIEW OF THE EUROPEAN STANDARDS DEALING
WITH ENERGY EFFICIENCY IN BUILDINGS 8 PART B – LOCAL SCENARIO
2.1 CEN Committees involved 8
2.2 Overview of the relationship of the standards OVERVIEW OF THE STANDARDS AND CODES
with the Directive 2002/91/EC 8 REGARDING BUILDING ENERGY PERFORMANCE
2.3 Methodology for calculating energy performance 8 In Italy 37
2.4 Energy performance certificate 10 In France 43
2.5 Periodic inspections of building systems 10 In Austria 51
In Romania 55
3. THE ENERGY BALANCE OF A BUILDING 12 In Germany 61
3.1 Energy balance of a building 12 In Poland 67
3.1.1 Energy use for space heating and cooling 12 In Spain 75
3.1.2 Energy use for domestic hot water preparation 12
3.1.3 Energy use for lighting 12
3.2 Understanding the energy balance of a building 12
3.2.1 Heat transfer 13
3.2.2 Ventilation 13
3.2.3 Internal heat gains 13
3.2.4 Solar heat gains 13
3.2.5 Thermal capacity of the building structure 14
3.2.6 Energy required by HVAC systems 14
3.2.7 Domestic hot water 14
3.2.8 Lighting 14
3.3 Calculation methodologies 14
3.4 The energy balance of a building as a design tool 15
4. THE ENERGY LABEL OF A BUILDING 17
4.1 Performance Index 17
4.2 Coverage of performance index
(what is included in an energy label) 17
3
6.
7. 1. SUMMARY OF EUROPEAN DIRECTIVES ABOUT
ENERGY EFFICIENCY IN BUILDINGS
INTRODUCTION 1.1.1 Objective
The problem of increasing energy efficiency in buildings As clearly stated in article 1, “The objective of this Directive is
has been recognized by the European Community for a to promote the improvement of the energy performance of
long time, since buildings account for approximately 40% buildings within the Community, taking into account outdoor
of the end users energy consumption in Europe. To this climatic and local conditions, as well as indoor climate require-
purpose, the Council Directive 93/76/EEC of 13 September ments and cost-effectiveness”
1993 to limit carbon dioxide emissions by improving energy
efficiency (SAVE) had many provisions about buildings, ex- The same article affirms:
plicitly indicating the necessity to implement actions in the “This Directive lays down requirements as regards:
following fields: (a) the general framework for a methodology of calculation
- energy certification of buildings, of the integrated energy performance of buildings;
- the billing of heating, air-conditioning and hot water costs (b) the application of minimum requirements on the energy
on the basis of actual consumption, performance of new buildings;
- third-party financing for energy efficiency investments in (c) the application of minimum requirements on the energy
the public sector, performance of large existing buildings that are subject
- thermal insulation of new buildings, to major renovation;
- regular inspection of boilers, (d) energy certification of buildings; and
- energy audits of undertakings with high energy consump- (e) regular inspection of boilers and of air-conditioning sys-
tion. tems in buildings and in addition an assessment of the heat-
ing installation in which the boilers are more than 15 years
This Directive is no longer in force having been repealed by old.”
Directive 2006/32/EC. Its contents have been largely super-
seded by new legislation (i.e. Dir. 2002/91/EC), summarized 1.1.2 Deadline for adoption
in the following point. The time frame for transposition is set out in article 15 that
states: “Member States shall bring into force the laws, regula-
1.1 DIRECTIVE 2002/91/EC ON THE ENERGY tions and administrative provisions necessary to comply with
PERFORMANCE OF BUILDINGS (EPBD) this Directive at the latest on 4 January 2006........” Unfortu-
As pointed out in the preamble of the Directive, “Council Di- nately, it seems that this process has taken a longer time for
rective 93/76/EEC of 13 September 1993 to limit carbon diox- many countries.
ide emissions by improving energy efficiency (SAVE)”.....” is now
starting to show some important benefits.” 1.1.3 Energy performance of buildings
“However, a complementary legal instrument is needed to lay In article 2 of the Directive, the following definition is given:
down more concrete actions with a view to achieving the great “ ‘energy performance of a building’: the amount of energy
unrealized potential for energy savings and reducing the large actually consumed or estimated to meet the different needs as-
differences between Member States’ results in this sector.” sociated with a standardized use of the building, which may
include, inter alias, heating, hot water heating, cooling, venti-
In other words, the implementation of the SAVE Directive lation and lighting.
was not completely satisfying: in particular, the energy cer- This amount shall be reflected in one or more numeric indi-
tification of buildings had a very limited application. For cators which have been calculated, taking into account insu-
these reasons, the Directive 2002/91/EC has been adopted. lation, technical and installation characteristics, design and
The main points considered by this directive are briefly out- positioning in relation to climatic aspects, solar exposure and
lined in the following paragraphs. influence of neighboring structures ,own-energy generation
and other factors, including indoor climate, that influence the
energy demand;”
5
8. 1.1.4 Methodology of calculation
of the energy performance
The Directive, in article 3, makes pro-
visions for the adoption of a harmo-
nized calculation methodology stat-
ing that:
“Member States shall apply a meth-
odology, at national or regional lev-
el, of calculation of the energy per-
formance of buildings on the basis
of the general framework set out …
This methodology shall be set at na-
tional or regional level.
The energy performance of a build-
ing shall be expressed in a transparent manner and may in- to promote energy efficient buildings and the energy per-
clude a CO2 emission indicator”. formance certificate of a building is considered a very im-
portant instrument to communicate energy efficiency to
1.1.5 Energy performance certificate the general public.
The energy performance certificate of a building is de-
fined, in article 2 of the Directive, as: 1.2 DIRECTIVE 1992/42/EEC ON EFFICIENCY
“....a certificate recognized by the Member State or a legal per- REqUIREMENTS FOR NEW HOT-WATER BOILERS FIRED
son designated by it, which includes the energy performance WITH LIqUID OR GASEOUS FUELS
of a building calculated according to a methodology based The European Community has taken into consideration not
on the general framework…”. only the performance of a building as a whole but also the
As specified in article 7: “The energy performance certificate efficiency of heating system components. In fact this di-
for buildings shall include reference values such as current le- rective about boilers, possibly one of the first to affect the
gal standards and benchmarks in order to make it possible for building sector, has been issued in order to improve “the
consumers to compare and assess the energy performance of efficiency of final energy demand”, to ensure a “prudent and
the building. The certificate shall be accompanied by recom- rational utilization of natural resources” and to eliminate
mendations for the cost-effective improvement of the energy “technical barriers”. To achieve these goals, it has established
performance.” (common) efficiency requirements for boilers to be sold and
installed across Europe. This Directive has been amended
In the same article 7, the following obligations are set forth: several times (by Directives 93/68/EEC, 2004/8/EC, 2005/32/
“Member States shall ensure that, when buildings are con- EC and 2008/28/EC) but the general framework has largely
structed, sold or rented out, an energy performance certificate remained the same.
is made available to the owner or by the owner to the prospec-
tive buyer or tenant, as the case might be. The validity of the 1.2.1 Objective
certificate shall not exceed 10 years.” and “Member States shall As stated in article 1: “This Directive, which comes under the
take measures to ensure that for buildings with a total useful SAVE program concerning the promotion of energy efficiency
floor area over 1 000 m2 occupied by public authorities and by in the Community, determines the efficiency requirements ap-
institutions providing public services to a large number of per- plicable to new hot-water boilers fired by liquid or gaseous fu-
sons and therefore frequently visited by these persons an ener- els with a rated output of no less than 4 kW and no more than
gy certificate, not older than 10 years, is placed in a prominent 400 kW, hereinafter called ‘boilers’”.
place clearly visible to the public.”
It is therefore clear that, according to this Directive, the en- 1.2.2 Efficiency requirements
ergy certification of a building has a special role as a mean The minimum efficiency requirements for boilers, at rated
6
9. (maximum) output and operating at 30 % part load, are es- e) Directive 2006/32/EC of the European Parliament and of
tablished in article 5 of the directive, as shown in the follow- the Council of 5 April 2006 on energy end-use efficien-
ing table (taken from the directive itself ): cy and energy services and repealing Council Directive
93/76/EEC.
1.3 OTHER DIRECTIVES
Other Directives affecting the building sector are men-
tioned in the following
a) Directive 2004/8/EC of the European Parliament and
of the Council of 11 February 2004 on the promotion
of cogeneration based on a useful heat demand in the
internal energy market and amending Directive 92/42/
EEC. This Directive promotes “high efficiency cogenera-
tion of heat and power based on useful heat demand and
primary energy savings....” with explicit reference to new
buildings with a total useful floor area over 1 000 m2 . It
must be noted that cogeneration (also called CHP, Com-
bined Heat and Power generation) as a system to achieve
energy efficiency for large buildings is cited in article 5 of
Directive 2002/91/EC. Moreover, the Directive also takes
into consideration micro-cogeneration units (i.e. units
with a maximum electric power capacity below 50 kWe)
that can also be of interest for small and medium sized
buildings.
b) Directive 2006/32/EC of the European Parliament and of
the Council of 5 April 2006 on energy end-use efficien-
cy and energy services and repealing Council Directive
93/76/EEC. This is a “blanket” Directive aimed at enhanc-
ing the cost-effective improvement of energy end-use
efficiency in the Member States. Inside there are many
provisions applicable to tertiary and residential sectors.
Article 17 repeals directive 93/76/EEC.
References
a) Council Directive 92/42/EEC of 21 May 1992 on efficiency
requirements for new hot-water boilers fired with liquid
or gaseous fuels
b) Council Directive 93/76/EEC of 13 September 1993 to
limit carbon dioxide emissions by improving energy ef-
ficiency (SAVE)
c) Directive 2002/91/EC of the European Parliament and of
the Council of 16 December 2002 on the energy perform-
ance of buildings (EPBD)
d) Directive 2004/8/EC of the European Parliament and of
the Council of 11 February 2004 on the promotion of co-
generation based on a useful heat demand in the internal
energy market and amending Directive 92/42/EEC
7
10. 2. OVERVIEW OF THE EUROPEAN STANDARDS DEALING
WITH ENERGY EFFICIENCY IN BUILDINGS
of buildings should follow the general framework set out in
INTRODUCTION
the Annex to the Directive 2002/917EC.
The practical application of all the provisions of Directive
While several standards cover specific aspects of the cal-
2002/91/EC, especially the ones regarding the calculation
culation process, the standards listed in Table 2.1 group
methodology to evaluate energy performance, require
together the various issues related to the four main areas
technical standards in order to perform these tasks in a uni-
covered by the EPBD.
form and consistent way. This aspect is considered expressly
in the Directive preamble which, in point 11, states: “The
In CEN/TR 15615:2008 it is explained that: “The main goal of
Commission intends further to develop standards such as EN
these standards is to facilitate the implementation of the Direc-
832 and prEN 13790, also including consideration of air-condi-
tive in Member States............It is up to national bodies to select
tioning systems and lighting”
one or more of the options given, depending on the purpose of
In fact, the European Commission and the European Free
the calculation and the type and complexity of the buildings
Trade Association has mandated the CEN (Mandate M/343
and their services.
- 2004) to prepare a series of standards aimed at European
harmonization of the methodology for the calculation of
The four main components set out in the Directive relate to:
the energy performance of buildings in order to help the
– calculation methodology;
Member States to implement Directive 2002/91/EC in a
– minimum energy performance requirements;
consistent way. Following mandate M343, the CEN has re-
– energy performance certificate;
vised many existing standards and prepared several new
– inspections of boilers and air-conditioning.”
ones, resulting in more than 40 documents as listed in the
“Umbrella Document” (CEN/TR 15615:2008). These include
EN number Content
28 new EN standards, 4 new EN ISO standards and more
Energy use, for space heating, cooling, ventilation,
than 15 revised standards. A complete description of the set domestic hot water and lighting, inclusive of sys-
EN 15603
of standards prepared can be found in document CEN/TR tem losses and auxiliary energy; and definition of
15615:2008 Explanation of the general relationship between energy ratings
Ways of expressing energy performance (for the
various European standards and the Energy Performance of
energy certificate) and ways of expressing require-
Buildings Directive (EPBD) - Umbrella Document. EN 15217
ments (for regulations); content and format of en-
ergy performance certificate
2.1 CEN COMMITTEES INVOLVED EN 15378 Boiler inspections
As indicated in CEN/TR 15615:2008: The Technical Commit- EN 15240 Air-conditioning inspections
Energy needs for heating and cooling (taking ac-
tees of CEN that were involved in the preparation of the stand- EN ISO 13790
count of losses and gains)
ards comprise:
– CEN/TC 89 Thermal performance of buildings and build- Table 2.1 – overview of the “high level” standards (from CEN/
ing components; TR 15615:2008)
– CEN/TC 156 Ventilation for buildings;
– CEN/TC 169 Light and lighting; 2.3 METHODOLOGY FOR CALCULATING
– CEN/TC 228 Heating systems in buildings; ENERGY PERFORMANCE
– CEN/TC 247 Building automation, controls and building As shown in Figure 2.1, the calculation process should start
management. with an evaluation of the energy needed to fulfill the user’s
The process has been overseen by CEN/BT TF 173, Energy per- requirements for heating, cooling, and lighting [1], and pro-
formance of buildings project group, which coordinated the ceed to include the “natural” energy gains [2], and obtain
work so as to ensure that standards prepared in different com- the building’s energy need [3]. It is then possible to estimate
mittees interface with each other in a suitable way. the delivered energy, recorded separately for each energy
carrier and inclusive of auxiliary energy [4], subtract the re-
2.2 OVERVIEW OF THE RELATIONSHIP OF THE newable energy produced on the building premises [5], and
STANDARDS WITH THE DIRECTIVE 2002/91/EC add the generated energy, produced on the premises and
The methodology for calculation of energy performances exported to the market [6].
8
11. As indicated in CEN/TR 15615:2008: EN ISO 13790 allows for
different levels of complexity,
simplified monthly or seasonal calculation;
simplified hourly calculation;
detailed calculation;
which can be chosen according to relevant criteria related to
the purpose of the calculation, such as new or existing build-
ings or type and/or complexity of the building and its services.
The calculations are based on specified boundary conditions of
indoor climate (EN 15251) and external climate. The simplified
calculation methods are fully specified in the EN ISO 13790. The
Figure 2.1 – schematic illustration of the calculation detailed calculation methods are not fully specified in EN ISO
process (from Umbrella document version V5). 13790, but any implementation needs to be validated accord-
ing to the criteria in EN 15265 and the input and boundary con-
Finally, the primary energy usage or the CO2 emissions asso- ditions are to be consistent with the fully specified methods.
ciated with the building [7] can be obtained, together with Zoning arrangements (applicable to all calculation methods)
the primary energy or CO2 emissions associated with on-site are described in EN ISO 13790.
generation, which is used on-site [8], and the primary en- The characteristics of the technical building systems are in-
ergy or CO2 savings associated with energy exported to the cluded via:
market [9], which is thus subtracted – heating systems, EN 15316-1, EN 15316-2-1, EN – 15316-
from [7].
In past years, the energy needs for
heating and cooling have been calcu-
lated according to:
EN 832:1998 “Thermal performance of
buildings- Calculation of energy use
for heating- Residential buildings” (no
longer in force).
EN ISO 13790:2004 “Thermal perform-
ance of buildings - Calculation of ener-
gy use for space heating” (superseded
EN 832 – applies to all buildings)
Today, the data necessary for energy
certification should be obtained ac-
cording to:
EN ISO 13790:2008 “Thermal perform-
ance of buildings - Calculation of ener-
gy use for space heating and cooling”
(updated EN ISO 13790 – applies also Figure 2.2 – Methodology for calculating energy performance (from CEN/TR
to cooling needs) 15615:2008).
9
12. 2-3, EN 15316-4 (various parts)
– and EN 15377;
– cooling systems, EN 15243;
– domestic hot water, EN 15316-3 (various parts);
– ventilation, EN 15241;
– lighting, EN 15193;
– integrated building automation and controls, EN 15232.
2.4 ENERGY PERFORMANCE CERTIFICATE
As illustrated in CEN/TR 15615:2008: “The indicative content
of the energy performance certificate is set out in EN 15217.
This standard also includes the definition of the energy per-
formance indicator and different options for the energy per-
formance classification.
EN 15603 provides ratings to define energy performance. The
categories for the purposes of certification are: Figure 2.4 – Example of certificate with 1 indicator without
calculated rating, based on calculated energy use under classification (from EN 15217:2007)
standardized occupancy conditions;
measured rating, based on metered energy” to the Energy Performance Regulation reference (i.e. the
minimum performance requirement for new buildings) and
According to standard EN 15217, different certificate for- the boundary between Class D and Class E corresponds to
mats can be used. the Building Stock reference (i.e. the energy performance
If classification is used, Annex B of standard EN 15217 sug- reached by about 50% of the existing buildings).
gests to use seven classes (A-G) distributed in such a way
that the boundary between Class B and Class C corresponds A couple of certificate examples, taken from Annex C of this
standard are shown in Figures 2.3 and 2.4.
2.5 PERIODIC INSPECTIONS OF BUILDING SYSTEMS
The standards dealing with periodic inspections are:
– for heating systems (and boilers): EN 15378
– for air conditioning systems: EN 15240
– for ventilation systems (not explicitly considered in EPBD)
EN 15239
References
a) CEN/TR 15615:2008, Explanation of the general relation-
ship between various European standards and the Ener-
gy Performance of Buildings Directive (EPBD) - Umbrella
Document
b) EN ISO 13790:2008, Energy performance of buildings -
Calculation of energy use for space heating and cooling)
c) EN 15193:2007, Energy performance of buildings - En-
ergy requirements for lighting
Figure 2.3 – Example of certificate with indicators and classifi- d) EN 15217:2007, Energy performance of buildings - Meth-
cation (from EN 15217:2007) ods for expressing energy performance and for energy
10
13. certification of buildings
e) EN 15232:2007, Energy performance of buildings - Im-
pact of Building Automation, Controls and Building Man-
agement
f ) EN 15239:2007, Ventilation for buildings - Energy per-
formance of buildings - Guidelines for inspection of ven-
tilation systems
g) EN 15240:2007, Ventilation for buildings - Energy per-
formance of buildings - Guidelines for inspection of air-
conditioning systems
h) EN 15241:2007, Ventilation for buildings - Calculation
methods for energy losses due to ventilation and infiltra-
tion in commercial buildings
i) EN 15243:2007, Ventilation for buildings - Calculation of
room temperatures and of load and energy for buildings
with room conditioning systems
j) EN 15251:2007, Indoor environmental input parameters
for design and assessment of energy performance of
buildings addressing indoor air quality, thermal environ-
ment, lighting and acoustics
k) EN 15265:2007, Energy performance of buildings - Cal-
culation of energy needs for space heating and cooling
using dynamic methods – General criteria and validation
procedures
l) EN 15316 -x-x :2007/2008, Heating systems in buildings
- Method for calculation of system energy requirements
and system efficiencies Various parts
m) EN 15377 -1,2,3 :2007, Heating systems in buildings - De-
sign of embedded water based surface heating and cool-
ing systems Parts 1-3
n) EN 15378:2007, Heating systems in buildings - Inspection
of boilers and heating systems
o) EN 15603:2008, Energy performance of buildings - Over-
all energy use and definition of energy ratings
11
14. 3. THE ENERGY BALANCE OF A BUILDING
INTRODUCTION tioned) space.
As pointed out in the previous chapters, a consequence of – Ventilation heat transfer (std. EN ISO 13789:2007): also
Directive 2002/91/EC has been the preparation of a large depends on the difference between internal and exter-
number of standards by CEN dealing with the calculation of nal temperature. Space ventilation can be obtained by
the energy performance of a building. Many people can be natural ventilation or through a mechanical ventilation
annoyed by the difficulties involved or see the calculations system (std. EN 15241:2007), in that case, there are ad-
as only mere bureaucratic paperwork. In reality, the energy ditional energy needs to be fulfilled (e.g. energy for fan
balance sheet of a building can be a very useful tool for the motors).
design of a new building or when considering the best strat- – Internal heat gains due to appliances, lighting fixtures,
egy to retrofit an existing one. people, losses from the space heating and/or hot water
system etc. Can also include negative gains from heat
3.1 ENERGY BALANCE OF A BUILDING sinks such as cooling systems etc.
The heat balance of a building includes several terms. They – Solar heat gains direct through windows or indirect
can be broadly divided into the three following main class- through opaque walls.
es: 1) energy used for heating, cooling and ventilation (std. – Heat stored in or released from the structures of the
EN ISO 13790:2008, 13789:2007); 2) energy used for domes- building.
tic hot water preparation (std. EN 15316 part 3-1, 3-2 and – The balance is then closed by the energy supplied by the
3-3:2007); 3) energy used for lighting (std. EN 15193:2007). heating system (EN 15316 -x-x :2007/2008, 15232:2007)
The calculation procedure can follow simplified quasi- in order to reach the internal set point winter tempera-
steady-state methods typically calculating the heat balance ture (std. EN ISO 15251:2007) or by the energy extract-
for each month (or even a whole season) or be performed ed by the cooling system (EN, 15243:2007) in order to
with a detailed dynamic simulation repeatedly calculating maintain the set point summer temperature (std. EN ISO
the heat balance over short periods and accounting for the 15251:2007), including system(s) losses and auxiliary en-
heat stored or released because of the thermal capacity of ergy, and deducting locally captured renewable energy
the building structures. The current national regulations (e.g. solar panels).
usually require only the (simplified, monthly based) calcu-
lation of the energy needed for winter heating, and, some- 3.1.2 Energy use for domestic hot water preparation
times, for domestic hot water production, but this should This item accounts for the energy used for the preparation
change in the next few years. and distribution of domestic hot water, including system
losses and auxiliary energy, and deducting locally captured
3.1.1 Energy use for space heating and cooling renewable energy (e.g. solar panels).
Includes the following terms (std. EN ISO 13790:2008).
– Transmission heat transfer between the internal (condi- 3.1.3 Energy use for lighting
tioned) space and the external environment (std. EN ISO This term accounts for the energy used for lighting (that is a
13789:2007). It is controlled by the difference between function of the daylight supply), including parasitic energy
internal and external temperature. The components in- (std. EN ISO 15193:2007).
volved are the opaque part of the envelope (walls, floors,
roof etc. - std. EN ISO 6946:2007, 13370:2007) and the 3.2 UNDERSTANDING THE ENERGY BALANCE OF A
glazed part of the envelope (windows - std. EN ISO 10077- BUILDING
1:2006, 10077-2:2003); in addition, also the thermal It is beyond the scope of this short guideline to delve into
bridges must be accounted for (std. EN ISO 10211:2007, the details of the preparation of the energy balance of
14683:2007). the building, which involves specialized issues, for exam-
– Heat transfer between contiguous spaces (because of ple, how to deal with heat losses toward terrain or toward
transmission and ventilation). It is controlled by the tem- unheated spaces, how to account for the various types of
perature difference between the internal (conditioned) thermal bridges, or how to compute the energy conversion
space and the contiguous (possibly unheated/uncondi- losses in the heating system. For these issues the interested
12
15. reader is referred to the European standards. The focus of ventilation system is used (std. EN 15241:2007), the design
this report is to provide a general overview of the building air change rate is known with reasonable accuracy (std. EN
energy balance. 13779:2004, 15242:2007). Natural ventilation rates (i.e. ob-
tained opening windows) can also be estimated (std. EN
3.2.1 HEAT TRANSFER 15242:2007). For residential buildings, natural ventilation
The heat losses through the envelope (std. EN ISO heat losses are usually evaluated assuming a conventional
13789:2007) take place along the following three paths. value for the air change rate around 0,5 ach (air changes per
hour), established at the national level. Whether this is a re-
– Heat transfer through opaque surfaces (e.g. walls, roof, alistic value or not is an issue for debate. Depending on the
floors): this is the most simple to control using low U val- climate, ventilation losses can account for a sizable amount
ues (std. EN ISO 6946:2007), that is, increasing the thick- of the total heating energy demand for a newly constructed
ness of the insulation layers, and in new buildings it is building (around 20-30 kWh m-2 year-1). To reduce this loss it
rarely a problem. Some difficulty can be encountered is possible to limit the air change rate, although this is not
when retrofitting existing buildings because of space recommended (air flow rates below 0,3-0,4 ach can lead to
constraints; unacceptable IAQ - indoor air quality), or to perform heat
– Heat transfer through glazed elements (e.g. windows - std. recovery from the exhausted air flow (quite easy if a me-
EN ISO 10077-1:2006, 10077-2:2003): the widespread chanical ventilation system is used). A possible strategy is to
availability of low-E (low emissivity) glass allows for U val- render the building airtight and perform the space ventila-
ues much lower than in the past, for both new construc- tion with a mechanical system, including a heat exchanger
tions and when retrofitting existing buildings. On the between exhaust and fresh supply air.
other hand, low-E glazed surfaces usually have a U value In the summer season, ventilation can be an effective way
in the range 1 - 1,5 Wm-2 K-1 , more than 3 times higher to remove heat from the building during the periods of the
with respect to opaque walls (that can easily have U val- day when the external air temperature is lower than the in-
ues lower than 0,3 - 0,4 Wm-2 K-1 ). A reasonable compro- ternal one, as usually happens during the night and in the
mise must then be reached between daylight supply and early morning.
winter solar heat gains on one side and increased heat
losses and (unwanted) summer solar heat gains on the 3.2.3 Internal heat gains
other side. The internal heat gains are usually generated by metabo-
– Heat transfer through thermal bridges (i.e. parts of the lism of people living inside the building, electric appliances
building envelope where heat flow is locally increased be- and lighting. In addition, there can be heat dissipated by
cause of shape and/or change of thickness and/or junc- or absorbed from mechanical systems (heating, ventilat-
tion between different materials - std. EN ISO 10211:2007, ing and cooling), water distribution/collection systems (hot
14683:2007): once a minor issue, the heat loss due to and mains water, sewage), and, in industrial and commercial
thermal bridges is now becoming a major problem. In buildings, processes and goods. For residential buildings,
fact, the trend to decrease the U values of windows and internal heat gains are usually evaluated assuming conven-
opaque walls (and then, the heat transfer through such tional values established at the national level, typically in
surfaces) is causing thermal bridges to become a major the range 2-5 W/m2. For non residential buildings, they can
cause of heat loss. In order to prepare a reliable estima- be evaluated according to std. EN 13779:2004.
tion of energy consumption they must be properly iden-
tified and accounted for. 3.2.4 Solar heat gains
The solar heat gains of a building take place mainly through
3.2.2 Ventilation glazed elements (e.g. windows). They are the result of the ra-
The losses due to ventilation (std- EN ISO 13789:2007) arise diation available in the building location, orientation of the
from the necessity to heat/cool the external air in order collecting surfaces, shading, solar transmittance of the glazed
to raise/lower the air temperature to the comfort value as elements, and of the thermal properties of the exposed areas.
suggested by std. EN ISO 15251:2007. When a mechanical During the winter season, solar heat gains can cover a con-
13
16. siderable fraction of the space heating energy needs if the insulated piping) and on site renewable energy captured
glazed surfaces are properly distributed (in addition, daylight are required.
supply should also be considered). In the summer season, ap-
propriate shading is used to control the (usually unwanted) 3.2.7 Domestic hot water
solar heat gains through glazed elements. The energy necessary to prepare domestic hot water is a
The net solar heat gains of the opaque portion of the enve- function of the volume of water needed, of the cold water
lope are usually negligible during the winter season. They supply temperature and of the characteristics of the genera-
can, instead, become an important factor in the summer tion and distribution system (std. EN 15316 part 3-1, 3-2 and
period, affecting thermal comfort and cooling needs, espe- 3-3 :2007). For residential buildings (e.g. single family dwell-
cially as a result of solar heat gains through the roof. ings), the domestic hot water volume is usually an assumed
conventional value based on the floor area or the number
3.2.5 Thermal capacity of the building structure of occupants, established at the national level. Solar collec-
The building structures can act as storage (capacitance), tors can cover a substantial fraction of the energy needed
where heat can be dynamically stored and released along for domestic hot water preparation.
time. These capabilities are often called “dynamic thermal
characteristics” or dynamic parameters” because they af- 3.2.8 Lighting
fect the behavior of a building in variable regime (std EN The energy used by a building for lighting can be calculated
ISO 13786:2007, 13789:2007) and not when things do not from the installed lighting power (luminaries and parasitic),
change, i.e. in steady state. Since the vast majority of build- daylight availability and occupancy schedule (std. EN ISO
ing components have almost the same value of specific heat 15193:2007). The installed lighting fixtures (and therefore
capacity, approximately 1000 J/ (kg K), the heat capacity of the installed power) should ensure adequate light to enable
building structures is directly proportional to their mass. people to perform visual tasks safely and efficiently (std. EN
The thermal capacity of a building (sometimes referred to as ISO 15251:2007, EN 12464-1:2002). For existing buildings,
thermal mass) is of major importance due to two issues: (1) direct metering of lighting circuits is recommended. For
the ability to exploit heat gains in winter (solar and internal); residential buildings, lighting energy needed calculations
and (2) the ability to smooth temperature peaks in summer. are usually not required.
3.2.6 Energy required by HVAC systems 3.3 CALCULATION METHODOLOGIES
To maintain the correct comfort conditions inside a build- As pointed out earlier (3.1), there are two basic calculation
ing (std. EN ISO 15251:2007), the HVAC system can be re- methods: quasi-steady-methods and dynamic methods.
quired to supply energy to the building during the heating Quasi-steady-methods calculate heat balance over long
season or to remove energy during the summer period. In periods (a month or a whole season) and take in account
addition, if there is a mechanical ventilation system, energy “dynamic effects” (i.e. building thermal capacity [see 3.2.5])
is required for fans operation. The overall (primary) energy through an empirically evaluated utilization factor (whose
required by the systems must be calculated considering symbol is η). In the winter season, the utilization factor for
the actual efficiency of the various components (e.g. boil- gains accounts for the fact that heat gains (solar and inter-
ers, chillers, etc) of the system, i.e. including auxiliary energy nal) only in part reduce the energy required for heating: for
and system losses (std. EN ISO 15603:2008, EN 15241:2007, example, excess solar heat gain could lead to unwanted
15243:2007, 15316 -x-x :2007/2008, ). Locally collected solar overheating of a room. A symmetrical approach is used for
or wind energy is not considered in the energy balance of thermal losses through ventilation and heat transfer during
the building (i.e. it is not added when computing the total the summer period (but, to date, the determination of the
primary energy delivered to a building as fuel or electricity). utilization factor for heat losses has not been validated in a
To contain the primary energy demand of a building then, it satisfactory way at the national level considering the various
is not enough to limit the energy needed for space heating climate conditions). This kind of method has been in use for
or cooling, but high efficiency generation systems (such as quite a long time, and gives reasonably accurate results for
condensing boilers), low loss distribution systems (e.g. well annual heating energy needs. Std. EN ISO 13790:2008 gives
14
17. Figure 3.1 – Schematic representation of the energy balance
of an existing (not “low energy”) building (it is assumed that Figure 3.2 – Schematic representation of the energy balance of
the average external air temperature and relative humidity in a new (“low energy”) building (it is assumed that the average
summer are such that the transmission and ventilation loads external air temperature and relative humidity in summer are
are negative). such that the transmission and ventilation loads are negative).
a complete description of a monthly quasi-steady-state cal- appropriate. For large commercial buildings, with com-
culation method (and gives the option to use a seasonal plicated HVAC plants, huge cooling loads and many occu-
method). This is the approach normally used for evaluating pants, a detailed dynamic simulation is probably required.
the heating energy use of a residential building.
Dynamic methods, instead, evaluate the energy balance 3.4 THE ENERGY BALANCE OF A BUILDING AS A
of a building over small time steps (typically one hour) and DESIGN TOOL
explicitly account for the effects of the heat stored in and The calculation of the energy balance of a building allows
released from the building mass because of its thermal ca- the user to know the overall energy use and, then to assess
pacity. Dynamic methods model heat transmission through the energy performance of the building. This should not
the envelope, heat losses due to ventilation, heat storage/ only be a legal requirement for the purpose of obtaining a
release in the building structure, and internal and solar heat building permit and/or an energy performance certificate,
gains in each building zone. The approach used can range but also a very useful tool to optimize the design of a new
from very detailed, 365 days simulations, to simple hourly building or to plan a retrofit.
reference day methods. Indications about performance cri- To obtain this result, a close cooperation between the
teria and requisites for detailed dynamic methods can be person(s) preparing the energy balance and the design
found in std. EN 15265:2007. Standardized input and out- team is required, since the energy balance should be pre-
put data and boundary conditions are specified by std. EN pared simultaneously with the design. It may be helpful to
ISO 13790:2008 to ensure compatibility and consistency establish an energy efficiency target at the beginning of
between different dynamic methods. Moreover, std. EN ISO a project, perhaps in terms of performance class as men-
13790:2008 fully specifies a simple hourly method modeling tioned in point 2.4.
each building zone as a five resistors one capacitor (5R1C) The most important point is to start preparing the energy
network with three-nodes. balance early in the process, when the design is in its initial
The choice of the appropriate method for the preparation phase: design changes prompted by energy performance
of the energy balance depends on the building considered consideration have very low or no costs associated when they
(size, main destination, number of occupants, occupancy are implemented in the initial design phase, but the addition-
schedule, etc.). For residential buildings with minor or no al costs can grow exponentially as the project progresses.
summer cooling, quasi-steady methods for the calculations Once the layout of the building has been drafted, efforts
of heating and domestic hot water energy needs are often should be made to determine the optimal orientation in
15
18. the local climate conditions. Attention should also be paid f ) EN ISO 13370:2007, Thermal performance of buildings -
to optimize active solar energy collection (thermal and/or Heat transfer via the ground - Calculation methods
photovoltaic): appropriate areas, with the right orientation g) EN ISO 13779:2004, Ventilation for non-residential build-
and slope must be made available. ings – Performance requirements for ventilation and
Fenestration placement and size should be carefully opti- room-conditioning systems
mized considering heat losses, heat gains (wanted in winter h) EN ISO 13786:2007, Thermal performance of building
and unwanted in summer) and day lighting. The influence components — Dynamic thermal characteristics — Cal-
of glazing type should also be analyzed. culation methods
The building envelope should also been designed with i) EN ISO 13789:2007, Thermal performance of buildings -
careful consideration of all possible thermal bridges (cor- Transmission and ventilation heat transfer coefficients -
ners, window frames, balconies, beams, etc.) and examining Calculation method
possible insulation alternatives. j) EN ISO 13790:2008, Energy performance of buildings -
The aforementioned activities should be iterated several Calculation of energy use for space heating and cooling)
times, each time checking the influence of the design choic- k) EN ISO 14683:2007, Thermal bridges in building construc-
es on the overall energy performance, and analyzing the tion - Linear thermal transmittance - Simplified methods
energy balance breakdown to understand the relative im- and default values
portance of the various items (heat losses through opaque l) EN 15193:2007, Energy performance of buildings - En-
flat components of the envelope, thermal bridges, glazed ergy requirements for lighting
surfaces, heat gains, etc.), and decide what actions to un- m) EN 15232:2007, Energy performance of buildings - Im-
dertake. pact of Building Automation, Controls and Building Man-
When the energy need for space heating (and, if the case agement
for space cooling) is within the desired target, the heating n) EN 15241:2007, Ventilation for buildings - Calculation
(or the HVAC) system and the domestic hot water system methods for energy losses due to ventilation and infiltra-
can be optimized (e.g. including renewable energy sources, tion in commercial buildings
such as solar and geothermal, and/or selecting high effi- o) EN 15242:2007, Ventilation for buildings - Calculation
ciency components). The systems optimization phase can methods for the determination of air flow rates in build-
also require some iterations. ings including infiltration
p) EN 15243:2007, Ventilation for buildings - Calculation of
The same approach can obviously be applied for retrofit room temperatures and of load and energy for buildings
planning and energy management purposes with room conditioning systems
q) EN 15251:2007, Indoor environmental input parameters
References for design and assessment of energy performance of
a) EN ISO 6946:2007, Building components and building el- buildings addressing indoor air quality, thermal environ-
ements –Thermal resistance and thermal transmittance – ment, lighting and acoustics
Calculation method r) EN 15265:2007, Energy performance of buildings - Cal-
b) EN ISO 10077-1:2006, Thermal performance of windows, culation of energy needs for space heating and cooling
doors and shutters - Calculation of thermal transmittance using dynamic methods – General criteria and validation
- Part 1: General procedures
c) EN ISO 10077-2:2003, Thermal performance of windows, s) EN 15316 -x-x :2007/2008, Heating systems in buildings
doors and shutters - Calculation of thermal transmittance - Method for calculation of system energy requirements
- Part 2: Numerical method for frames and system efficiencies - Various parts
d) EN ISO 10211:2007, Thermal bridges in building construc- t) EN 15377 -1,2,3 :2007, Heating systems in buildings - De-
tion - Heat flows and surface temperatures - Detailed cal- sign of embedded water based surface heating and cool-
culations ing systems Parts 1-3
e) EN 12464-1:2002, Light and lighting — Lighting of work u) N 15603:2008, Energy performance of buildings - Overall
E
places — Part 1: Indoor work places energy use and definition of energy ratings
16
19. 4. THE ENERGY LABEL OF A BUILDING
Introduction between analogous indexes. For this reason, it should be
It can be reasonably expected that the energy performance clearly stated what is actually included in an energy label
certification will be in widespread use in the coming years. It’s and what is not.
highly probable that the energy certificate will include some
kind of energy classification in order to express the rating of 4.3 Conventional values
a building in a form easy to communicate and to understand The performance of a building is evaluated in a standard
even for the lay-men. This is very important in order to drive climate with a standard pattern of use. In reality, there are
the building market toward a better quality. This issue is criti- meteorological oscillations and varying end user behaviors.
cal because the classification is in many respects a complex In this case, the cautionary warning used in the car market
process aimed at communicating to the end user the energy “your mileage may vary” also applies in the building context.
performance in a simple and effective way. The real value of energy ratings is the power of comparison:
the end user can compare similar buildings in a similar lo-
4.1 Performance index cation easily identifying the one with the best relative per-
To assess the energy performance of a building, the starting formance.
point is the energy balance mentioned previously; as an al-
ternative, for existing buildings, actual energy usage can be References
metered. However, in order to communicate it effectively, – EN 15217:2007, Energy performance of buildings - Meth-
the performance of a building is usually translated in a sin- ods for expressing energy performance and for energy
gle (synthesis) index or in a very short list of indexes (the certification of buildings
parameter most frequently used is the ratio of energy used – EN 15603:2008, Energy performance of buildings - Over-
vs. floor area often measured in kWh/m2) (EN 15217:2007). all energy use and definition of energy ratings
This index is then contextualized in a scale (so that it is visu-
ally evident where the index lays between the minimum
and maximum performance range) or assigned to a single
class selected within a limited number of classes (typically
ranging from A to G).
4.2 Coverage of performance index (what is included in
an energy label)
The evaluation of the energy performance is an evolution-
ary process: there is a long standing practice for computing
the energy use for space heating, while other energy usage
types, such as cooling and lighting energy needs, have not
been considered as much in past years. For these reasons,
in many countries, the first instance of energy classification
will include only a subset of energy needs.
Some examples include:
energy consumption for space heating based on envelope
performance (for heat transfer and ventilation);
overall energy consumption for space heating based on pri-
mary energy input (including losses in the heating system);
overall energy consumption for space heating and domestic
hot water based on primary energy input (including losses
in the heating system);
It must be clear that the comparison can be performed only
17
20. 5. APPLICABLE BEST PRACTICES
Introduction so to avoid thermal bridges. Special care must be paid to
While building best practices are strongly dependent on the shutters (and to roller shutter boxes). All windows must have
local context, some general indications applicable to the shadings to control summer heat gains, externally placed.
whole European context can nevertheless be given. These Proper lighting design and practice must be followed to
indications can be grouped in four general areas: high per- make sure that at least a reasonable amount of daylight
formance envelope, exploitation of renewable systems and penetrates in the spaces meant for human occupancy (EN
energy efficient systems and certification. 15193 provides details of daylight availability and estima-
tions).
5.1 ENVELOPE PERFORMANCE
A properly designed envelope is of fundamental impor- Since ventilation heat losses are a major factor (in many Eu-
tance to achieve a highly efficient building. ropean climates, natural ventilation can account up to 20-30
Compact buildings, with a low surface to volume ratio, have kWh m-2 of the heating energy needs), the envelope should
better energy performance, but compactness should not be be designed and built so that it is airtight and avoids un-
stretched to the point of excessively decreasing daylight in wanted external air infiltrations. While the occupants must
internal areas, far away from windows. always have the option to open windows (because of well-
being considerations and also because in mild climate peri-
The insulation of opaque walls should be the best quality ods, natural ventilation can still be the most efficient option)
possible and, in any case, the U value should not exceed the installation of a controlled ventilation system should be
0,25 Wm-2 K-1. Whenever possible, the insulation layer should carefully evaluated.
be placed on the outer side of the wall to minimize vapor
condensation risks and to increase the availability of ther- 5.2 RENEWABLE ENERGY SYSTEMS
mal mass. When designing a new building, or retrofitting an existing
Every attention should be paid to avoid local heat flux in- one, proper consideration should be given to renewable en-
creases (thermal bridges) due to material inconsistencies ergy system.
and/or shape. This requires extreme attention to details Thermal solar collectors for domestic hot water prepara-
starting from the design phase and ensuring the avail- tion have now reached a degree of product maturity and
ability of skilled people in the construction yard. A special financial sustainability such that it’s hardly justifiable not in-
challenge comes from balconies and other protruding ele- stalling them in every new/retrofitted building. Depending
ments because of cantilevered beams: cantilevered beams, on local legislation, available financial incentives, and elec-
obviously, cannot be cut to insert thermal insulation and so tric power sale/ buying tariffs, the installation of PV panels
external frames supporting balconies and other appendixes should also be carefully considered. To make installation of
should be used whenever possible. solar panels (thermal and PV) actually feasible, financially at-
tractive and aesthetically pleasant provisions must be made
Window quality should also be the best possible with low-e for adequate available surfaces (with proper size and orien-
glass panes and high performance frames (overall U value tation), possibly on the roof.
should not exceed 1,25 Wm-2 K-1). The windows should be
properly distributed in order to grant adequate solar gains For low energy buildings, heat pumps can also often be a
in winter, avoid excess solar gains in summer, and ensure ad- viable option, this is even truer if the wells for geothermal
equate daylight supply. A proper balance must be achieved energy exploitation are carefully coordinated with founda-
considering the overall performance along the year: win- tion walls and beams.
dows that are too small may be a problem (not enough
daylight supply, impaired well being) but windows without Renewable energy systems must be coordinated with the
shadings and that are too large can also be a problem (win- other mechanical/electric systems found in the building
ter heat losses, summer overheating, glare and blinding). (heating, ventilation, etc.) For example, heat pumps (and to
The window frame (and counter-frame) must be properly se- an extent, the excess heat coming form solar thermal panel)
lected, seated in place and aligned with the insulation layer are best matched with low temperature heating systems.
18
21. classes. The energy performance certification is also impor-
5.3 ENERGY EFFICIENT SYSTEMS tant with respect to renovating existing buildings: despite
the fact that for some existing buildings, higher energy per-
The design and actual construction should strive to obtain formance classes may not be practically reachable, it is nev-
the highest efficiency attainable from all the building sys- ertheless important to attest the improvement that could
tems. be obtained using best practices.
The heating systems should be of the low temperature type.
If embedded water based surface heating and cooling sys-
tems are used, great care must be taken to avoid heat losses
toward the ground or other unheated spaces (basement,
etc.), laying in place adequate insulation (embedded water
based surface heating and cooling systems will substan-
tially raise the temperature in winter and substantially lower
the temperature in summer of the building structure they
are embedded in, potentially increasing losses from such
structure if adequate insulation is not in place).
If fossil fuels are used for heat generation, such as oil or nat-
ural gas, high efficiency condensing boilers should be used.
The hot/chilled water distribution pipe network must be
properly sized in order to minimize pressure losses.
The energy supply for auxiliary electrical equipment (e.g.
pumps and fans) must be minimized through design of an
(air and/or water) distribution network requiring low pres-
sure head, and selection of equipment with proper size and
high efficiency (i.e. variable velocity pumps/fans). Electric
heating systems should be avoided unless the primary en-
ergy input can be proved to be comparable with other ones.
5.4 CERTIFICATION
As pointed out previous, the certification process is fun-
damental for ensuring the performance of a building and
to communicate it in an effective way. Moreover, properly
monitoring each phase (design, construction and opera-
tion) of the process leading to a “best practice” building,
as required by “certification protocols”, will ensure that the
desired building performance can be actually achieved and
demonstrated to the prospective owner. For new buildings,
the target performance should be substantially higher than
the minimum level required by national/and or local regula-
tions (as the bare minimum required is usually a level that
is easily obtainable without any special provisions and, as
such, can hardly be qualified as a best practice). Therefore,
“best practice” buildings should reach higher performance
19
22. 6. SOME EXAMPLES OF BEST PRACTICES
6.3 BEST PRACTICE 1: EFFICIENT INSULATION
BEST PRACTICES EXAMPLE IN FRANCE
6.1 BUILDING NAME AND IDENTIFICATION: “THE PARk
OF MUEHLMATTEN” IN BOLWILLER
The housing building “The Park of Muehlmatten” is a mul-
tigenerational residence of 15 flats based on a low energy
conception. It is located in Bollwiller in Alsace (continental
climate). This building, with an area of 1.338 m², is classified
as a level A according to the energy scale and answers at the
BBC-effinergie label criteria.
Umax
U
Designation Type value Information
(W/m².K)
(RT2005)
Exterior wall exterior wall 0,14 0,45 OK
Basement wall interior wall 0,285 0,45 OK
Interior wall
on common interior wall 0,421 0,45 OK
Pictures of the whole building. property
Base floor
6.2 OUTLINE OF THE APPLIED BEST PRACTICES interior floor 0,173 0,4 OK
on basement
It is a traditional French structure based on brick. Its insu- Upper floor
exterior wall 0,123 0,28 OK
lation is an external envelope made of polystyrene, 20cm on attic
thick. Its double glazed windows are low-e filled with argon. Terrace roof roof 0,143 0,34 OK
Terraces are isolated from the building thanks to rupture Windows windows 1,1 2,6 OK
of thermal bridges systems. The ventilation system is com-
posed of a mechanical ventilation with heat recovery. The
6.4 BEST PRACTICE 2: RATIONALISATION OF THE
airtightness of the building is optimized and is 0,6 m3/h/
CONSTRUCTION
m², with a pressure difference of 4 Pa. The heating system
The construction program has been conceptualized in order
is based on a high performance gas fired condensing boiler
to be transposable, with utilization of tested building ma-
with floor embedded heating system. Hot sanitary water is
terials. It permits easy implementation and satisfies French
produced by a collective solar heating system. The summer
standards. This low energy building costs 15% more than
comfort is ensured by a solar shading system. Thus, there is
the same standard building. The extra investment cost will
no need of a cooling system in the building.
be balanced by lower operating costs.
20
23. BEST PRACTICES EXAMPLE IN ITALY ly insulated envelope (exp. roof and exterior walls), care to
avoid thermal bridges, and efficient low temperature heat-
6.5 BUILDING NAME AND IDENTIFICATION ing systems using renewable heat sources such as wood
The building, designed by Architect Pierpaolo Botteon, is a pellets and solar panels. In addition, great attention has
two-family house located in Pergine Valsugana (TRENTO – been paid to the global sustainability of the building, using
Italy), town with 20 000 inhabitants, elevation 490 m ASL. wood for the main structure and low impact insulating ma-
Each unit has a floor area equal to approximately 200 m2, terials whenever possible.
and a volume equal to approximately 500 m3. The internal
climate is controlled through a low temperature hydronic
radiant floor heating system, and the heat source is a wood
pellet boiler integrated with solar heat panels. The energy
use for heating is less than 50 kWh/m2 per year. The maxi-
mum value permitted by the Italian regulation for the con-
sidered climate (3147 degree days) is equal to about 100
kWh/m2.
Views of the construction yard, showing the wood frame struc-
ture.
6.7 BEST PRACTICE 1: WELL INSULATED EXTERNAL
WALLS
The external walls have been insulated using, on the outer
side, 12 cm (6+6) of wood fiber with a certified thermal con-
ductivity λ= 0,045 W / (m K) and, on the inside, 5 cm of linen
Views of the finished “casa a Susà” building. fiber with a thermal conductivity λ= 0,040 W / (m K). The re-
sulting wall has a total thickness of 22,1 cm and a U value
6.6 OUTLINE OF THE APPLIED BEST PRACTICES lower than 0,2 W / (m2 K). The maximum value permitted by
Several measures have been applied in order to achieve the Italian regulations for this climate is U = 0,35 W / (m2 K).
high energy performance in this building, including a high-
21
24. 6.9 BEST PRACTICE 3: AVOIDANCE OF THERMAL
BRIDGES
Great care has been taken to avoid the formation of thermal
bridges. Some of the adopted measures are shown in the
following pictures.
View of the external wood fiber insulation (left), and of the in-
ternal linen fiber insulation (right) during the laying in place.
6.8 BEST PRACTICE 2: WELL INSULATED ROOF
The roof has been insulated using 18 cm of wood fiber based
insulating package, with a certified thermal conductivity λ=
0,040 W / (m K) and density equal to 160 kg/m3. This not only
ensures protection during the winter season, but also, due
to the high thermal mass, provides protection against over-
heating in summer. The material has been laid in place with
adequate protection against rain water and moisture migra-
Balcony beam frame,
tion. The resulting structure has a U value lower than 0,2 W/ avoiding cantilevered
(m2 K). The maximum value permitted by the Italian regula- concrete beams
tions for this climate is U = 0,31 W/(m2 K). protruding from
the heated space
Additional insulation to avoid the thermal bridge due to the
joint between the wood frame and the concrete basement.
View of the wood fiber
insulation during laying
in place on the roof structure.
Floor slab and beams for balcony.
22
25. BEST PRACTICES EXAMPLE IN POLAND
6.10 BUILDING NAME AND IDENTIFICATION
PASSIVE HOUSE is located in Smolec, near Wrocław (Poland)
between marine and continental climates. It is a residential
house, however, it is used for conferences, training purpos-
es, and promotion of low energy buildings. It was designed
and built in 2007 by Design Office Lipinski Domy. It is the
first building with a certificate of Passive House of Darm-
stadt Institute.
Figure 1. The first certified passive house in Poland carried out
in 2006 in Smolec near Wrocław. Detached building, design: Dr
Ludwika Juchniewicz-Lipińska, Dr. Miłosz Lipiński. Below – the
view: ground floor and garret. (L.J.L.)
6.11 OUTLINE OF THE APPLIED BEST PRACTICES
The architecture of the building is based on a single family
house. It is created strictly with passive house requirements
keeping its simple construction, innovative technology,
building materials of good quality, and moderate prices.
The design, as well as construction, guarantees maximum
reduction of thermal heat losses while gaining as much so-
lar energy as possible at the same time. The best structural
solutions applied in the house are window openings, insula-
tion system, and ventilation system with heat recovery. The
building is equipped with a renewable energy generator,
such as solar collectors. It is centrally situated on the steep,
two-sided roof.
The kitchen with dining room has a storage room located
behind. In this storage room, there is equipment replacing
the traditional heating system. This is the main heat ex-
changer - electric device - designed only for passive houses
only. This heat exchanger is called Vitotres 343 and is 60 cm
wide. In this particular housing equipment there are other
essential heating and ventilating devices which are well-
fitted, manufactured mounted and tested. Inside there are:
air heat pump, ventilating and heat exchange centre, wa-
ter heater with a capacity of 250 l with a pipe, that is inte-
grated with the solar installation, electric thermal input, and
23
26. a weather regulator. The weather regulator controls all of 6.13 BEST PRACTICE 2: THERMAL INSULATION
these devices. The most relevant technology applied in the building is the
elimination of thermal bridges from the whole construction
6.12 BEST PRACTICE 1: WINDOWS OPENING (external partition, partition bonding etc). It is substituted
The window openings are arranged in such a way so as to with a continuous thermal insulation layer of 30-44 cm thick,
guarantee a good amount of natural light (according to with the objective of achieving passive house standards. Al-
polish norms). The size of the windows minimizes heat loss- though foundation walls have got thermal bricks, applying
es. The innovative element, such as large glazed planes in insulating plinth hollow bricks reduces cooling discomfort.
the kitchen and living room, magnify the house area (131,4 The thermal transmittance of the external walls, roof, ceil-
m2) making it more spacious. Large triple windows are ori- ing, and floor is U=0,1 W/m2K, and the foundation and floor
ented towards the south to maximize passive solar gain. The plate is U=0,12 W/m2K.
solar collector in the building roof, apart from the innova- The walls are made from prefabricated elements consisting
tive character of the house, guarantees solar gains. The an- of a mixture of concrete and expanded clay (pallets). The
nual of requirement for heat demand of the building is 13,7 insulating material is a silver-grey foam polystyrene. It con-
kWh/m2. tains graphite (lower density q=15 kg/m3 means better in-
sulation properties). The foamed polystyrene is based on an
innovative raw material (Neopor) with thermal conductivity
λ≤0,031 W/m2K.
Figure 3. Axonometric section through passive house. Innova-
tive technology, simple and economically effective solution
elaborated to traditional design. Design Office Lipiński Domy,
Wrocław 2005. (L.J.L.)
6.14 BEST PRACTICE 3: VENTILATION SYSTEM
The building is equipped with mechanical ventilation with
a heat recovery device. It is a compact device which main-
tains air quality in the passive house. It has an integrated
supply-exhaust ventilator with heat exchanger. In addition,
a ground heat exchanger is included.
Figure 2. The south elevation of the building. (L.J.L.).
24
27. BEST PRACTICE EXAMPLE IN SPAIN near the top is opened to vent the hot air to the outside.
Such venting makes the Trombe wall act as a solar chimney
6.15 BUILDING NAME AND IDENTIFICATION pumping fresh air through the house during the day, even if
CENIFER building it is located in Pamplona (Spain) in a there is no breeze.
Southern European climate. It is a non residential building
devoted to conferences and training. The building renova- The annual thermal production is 17.970 KWh. The emis-
tion was carried out in the year 2000 with bioclimatic cri- sions savings per year are 30Kg SO, 10 Kg NO and 2.640 Kg
teria. CO2.
6.16 OUTLINE OF
THE APPLIED BEST 6.18 BEST PRACTICE 2: GROUND WATER COOLING
PRACTICES For heating and cooling systems, the building has a radiant
The most relevant ar- floor installed. It consists of reticulated polyethylene pipes
chitectural solutions embedded in the floor, through which water is circulated.
applied in the building The subsoil water circulates through the system in the sum-
are floor radiant heat- mer period providing summer cooling.
ing, Trombe walls and a
greenhouse to minimize
heating consumption.
The building includes re-
newable energy genera-
tion capabilities, such as
photovoltaic panels, so- Annual thermal production 12.558 KWh. Emission savings per
lar thermal panels with year are 3Kg SO, 1 Kg NO2 and 248 Kg CO2.
Views of the CENIFER building. heat storage system,
and geothermal cooling
system. The Cenifer building incorporates ICT-s solutions 6.19 BEST PRACTICE 3: SOLAR THERMAL
to achieve an energy efficient performance. The building INSTALLATION
is equipped with a presence sensor, temperature sensors, The building obtains hot water and heating from flat solar
humidity sensors and light sensor with a centralized moni- collectors located in the building roof. The building has a
toring system that tracks data coming from sensors, energy storage system for hot water. The objective is to store the
generation and storing systems. exceeding energy from thermal collectors using it for heat-
ing during low solar radiation days. It can provide 22 days of
6.17 BEST PRACTICE 1: TROMBE WALL heating without solar radiation.
The Trombe wall is a sun-facing glass wall attached to a solid
wall that contains a small internal ventilated chamber. Dur-
ing winter time, sunlight shines through the insulated glaz-
ing and warms the sur-
Annual thermal
face of the thermal mass.
production is
The cold air coming 61.220 KWh.
from inside or outside Emission savings
(to guarantee air renova- per year are 102Kg SO,
tion) is heated and it is 32 Kg NO2
introduced inside from and 8.251 Kg CO2.
the upper side of the
wall. During summer pe-
riods, the exhaust vent
25
28. BEST PRACTICE EXAMPLE IN ROMANIA be removed. Afterwards, the following layers will be con-
structed:
6.20 BUILDING NAME AND IDENTIFICATION – a layer of M100 plaster with variable thickness;
The building under discussion is an apartment block locat- – a stable of 1 K Zpezial will be applied cold (as a barrier
ed in the Timisoara on the Arad Street no.10. Construction of against the vapors and an adhesive layer for the basaltic
the building was completed in 1976 and has a cross-shaped glass wadding).
structure with Basement + Ground Floor + 10 floors and a – Basaltic glass wadding, 12 cm thick, lined with asphalt;
technical level (trolley room). The basement includes 14 ga- – Hydro insulating membrane, protected by sand;
rage spaces and 44 lodges. – Hydro insulating membrane protected by slate.
The block has 88 flats, 8 flats on each floor. All floors, includ- To expel the moisture, double vents were used, one for each
ing the ground floor, are identical, with 4 one-room flats, 3 70 m2 surface area
three-room flats and 1 flat with 4 rooms. Expected life time of the energy saving solution: NS = 20
General information on the building: years.
House room: 1955,47 m2
Active surface in the heated space: 4842,86 m2;
Active volume in the heated space: 13251,82 m3;
Total building volume: 16192,61 m3;
Information on the heating system
Type of heating system: central heating with static elements
Amount of heat for calculus: 453.000 kcal/h
Connection to the central heating plant: single connection
Heat meter: installed
Thermal and hydraulic elements: not installed Views of the roof terrace.
6.23 BEST PRACTICE 2: THERMAL INSULATION OF
THE EXTERNAL WALLS USING A 10 CM LAYER OF
CELLULAR POLYSTYRENE
The thermal insulation system of the walls consists of:
– proper closing of the horizontal joints (to prevent the in-
trusion of microorganisms)
– adhesive layer for the polystyrene;
– cellular polystyrene, 10 cm thick layer;
– glass fiber not covered with an adhesive layer for the
Views of the building before rehabilitation. spatula
– primer layer with set in and whitewash
6.21 OUTLINE OF THE APPLIED BEST PRACTICE – ornamental plastering
Several measures have been taken in order to achieve high In order to reduce the negative influence of thermal bridges,
energy performance in this building including: thermal in- the solutions are applied in a manner designed to conserve
sulation of the roof terrace, thermal insulation of the enve- the continuity of the thermal insulation layer, especially in
lope, thermal insulation of the ceiling over the cold base- seating and attic joining points (double insulation layers
ment, thermal and hydro insulation of the basement wall. on both sides). On the outline of the outside wood window
frames, a thermal insulation covering of cellular polystyrene
6.22 BEST PRACTICE 1: THERMAL INSULATION (2 cm thick) on the external sills and window ledges is pro-
OF THE ROOF TERRACE vided.
All existing layers of thermal and/or hydro-insulation will In order to avoid fire to spread from one level to another
26
