University of Istanbul, Turkey
University of Torino, Italy
Congress was held on 3–4 October 2013, in İstanbul,
Turkey. Climamed conferences are organized by 5
member countries of the REHVA. Founders of Climamed
conferences are France, Italy, Spain and Portugal. Turkey joined this group
later 4 years ago. Main goal of the conference is discussing regional topics of
the Mediterranean climate. This conference was the 7th conference in series
of the congress was the nZEB, especially approaches
to the nZEB in these Mediterranean countries. 159
abstracts were received from not only member counties but from 21 countries in
the region and all over the world. Finally 90 full papers included in the
proceedings book and 66 papers presented orally during the congress and 11
posters were exposed. 22 Technical Sessions were held in 7 parallel rooms
during the congress. Technical sessions were designed according to congress
themes. Besides, 3 invited lectures were also presented during the congress and
a panel was held. Additionally, a seminar was organized by the Eurovent. 429 participants were registered formally at the
conference. Including guests and other accompanying people, more than 500
people attended the conference.
Nearly Zero Energy
of the congresswas actually “net zero energy buildings”
however the focus was on the nearly zero energy buildings. After EPBD recast
announced, nZEB is on the agenda of the EU building
and HVAC sector. This topic has been discussed and studied extensively during
the conference. Especially approaching nZEB in terms
of Mediterranean climate, Mediterranean traditions and finance was the focus
We certainly can achieve the nZEB target for new buildings as we achieved the building performance evolution of the last 12 years in Europe. Boundary conditions definition of the global performance evaluation needs still some work and common consensus. But the move towards nZEBs is going to be a major shift, almost a revolution, requiring many changes even to the life of professionals. Buildings of the future shall be quite different from what we are used to design and use today
concept of nearly zero energy building was illustrated, introducing the basic
concept of “nZEB”: low energy demand, high energy
efficiency of the system, energy demand cover by RES produced in situ or
definition should be clarified first of all. It was highlighted that the
indicator to classify the energy performance of an nZEB
is expressed in term of primary energy. The boundary where to consider the
primary energy indicators has to be clearly accepted by all the countries – a
discussion is ongoing at CEN level about the new standard to be adopted.
Moreover, a big challenge is how to traduce the “primary energy indicator” in a
comprehensible indicator for the market: this issue is at this stage too much
academic and it is important to translate this concept to the policy makers,
investors and final users.
The other ambiguity is related to renewable energy production on-site or nearby. The definition of nearby is not clear enough. Actually the nZEB concept can be achieved more successfully by designing group of buildings, districts, cities instead of individual buildings. A successful nZEB design ensures a good architectural and urban integration.
The major challenge is still applying nZEB approach /concept to present building stock. It is expressed as nZERB (nearly zero energy retrofitted buildings). We need to develop this nZERB concept. Urban transformation processes going on especially in developing countries for example in Turkey can be used effectively transforming present building stock.
measures should take into account economical/financial aspects using a cost
optimal approach (Figure 1). The cost optimality has always to
be considered when defining the targets of nZEB and
cost optimal solutions cannot be achieved without integrated design.
Nearly zero energy buildings may not be cost optimal with current technology
and construction practice.
embodied energy in the building itself and in its HVAC systems (including
renewable energy generation) is very important. Without considering embodied
energy satisfactory evaluation of measures cannot be done.
yet a clear lack of consensus on what anZEB should be in the warmer south European climates, where
summer cooling plays a fundamental role (Figure 2):
but not too much insulation;
· Role of natural and mechanical ventilation
This is a
challenge at design stage. It is evident that a common and unique vision about
“what anZEB is” has yet to
be found for the Med region.
Figure 2. Typical Office Building Energy Need over a Year in Mediterranean Climate
The situation in different
Mediterranean countries has been analyzed:
the process, started with the energy certification RT2012, aimed at increasing
the energy performance of buildings is going on towards nearly zero energy
buildings (Figure 3). The new indications of the
protocols are addressed firstly to optimize the building envelope and to
control the air permeability of buildings. Moreover, the energy classification
is now referred to absolute values instead of to the comparison with reference
building. New voluntary labels have been set up in order to promote buildings
even more efficient than the new regulation; in particular “BEPOS effinergie” is aimed to promote the design and construction
of high performing buildings towards positive energy buildings.
Figure 3.Evolution of limit for primary energy consumption in French
the transposition of the EPBD recast has been done in June 2013 by a national
law. Now the national law has to be converted into regional laws. The process
will require time. By now, only a couple of regions have activated tables to
implement the nZEB concept. Critical aspects for
these implementations have been highlighted. First, to avoid a “copy and paste”
tendency that is to transfer the experiences from Germany and the Scandinavian
countries without a critical investigation: in Mediterranean climate,
super-insulation is not required, thermal mass activation is needed, mechanical
ventilation is not always economically convenient, punctual control of solar
radiation along the year is absolutely required.
Portugal, the process of implementing the nZEB
concept has to be yet fully developed. There is a definition and a concept, but
no values yet. It is highlighted that a major goal is to handle retrofitted
buildings: how to plan a deep renovation of the existing building stock toward
nearly zero energy building while keeping the costs under control. An open
discussion is related to ventilation: natural or mechanical? The national
tradition is for natural ventilation: in fact, in the Mediterranean areas, the
temperature differences between outdoors and indoors is quite low also in the
extreme season. The energy production by RES is also discussed: the use of RES
produced “nearby” is considered as locally produced by the Portuguese
interpretation, in RES installations specifically linked to a building or a
group of buildings.
the new concepts about nZEB have been transposed in a
law in September 2013. The process is considered as a natural evolution of the
energy certification, using the same tools and approach. Basically, the
requirements about the building energy performances have been incremented (for
example, lower thermal transmittance are required) in order to create a process
stating an ambitious program to follow the EU indications. The first step is
the definition of reference buildings for the residential sector, and the
application of packages of retrofit measures for cost optimality
Indoor air quality and nZEB
is in the focal point of the whole air conditioning activities. We air
condition the buildings for occupant’s comfort and health, we need to give a comfortable and reliable environment to occupants. Productivity is the primary
criteria designing some type of buildings, such as office buildings or
educational facilities. It is necessary to satisfy the occupant’s requirements
in nZEB. The design should consider the IAQ
The other very important issue is the occupant behaviour on energy consumption. Occupant behaviour can impact the energy consumption with a factor 3–6. Often main reason why predicted energy use does not match measured energy use is the occupant behaviour. Assumptions regarding occupant behaviour are used as input parameters to energy calculation. Suitable models for occupant behaviour are required for a better prediction of energy consumptions of buildings.
Findings of a presented study demonstrated that predefined heating
set-point preferences and air change rates used as assumption in building
energy simulation are far away from actual occupant’s preferences in buildings.
Results of the study highlight significant influences of occupant behavior on
the building energy demands. Energy consumption in the simulated high
performing building in which occupants personal control is performed by probabilistic
functions, raised up to 36% in comparison to the high
performing building where the occupants’ interaction with the controls is
regulated in a deterministic way by fixed schedules.
ofIndoor Environmental QualityStandard EN15251, need to be complying with nZEB concept. Standard EN15251 brings new approaches.
Instead of absolute values, categories and ranges are defined. Moreover,
adaptive comfort approach is introduced.
Table 1. The recommended criteria are given for several categories (EN 15251:2007).
High level of expectation and is recommended for spaces occupied by very sensitive and fragile persons with special requirements like handicapped, sick, very young children and elderly persons
Normal level of expectation and should be used for new buildings and renovations
An acceptable, moderate level of expectation and may be used for existing buildings
A level that may cause some discomfort; but no health risk.
Outside categories. This should only be accepted for a limited part of the year
This European Standard specifies the indoor environmental parameters which have an impact on the energy performance of buildings.
points are effective both on energy consumption, comfort and productivity.
sensors can effectively be used in ventilation applications, especially in
demand controlled ventilation applications.
Ventilation rates are specified
for different categories and applications.
Ventilation rates should
consider both people and building (Figure 4)
Air cleaners and ventilation
can be combined.
behavior should be considered.
Air change has been measured in 500 Danish homes. In more than half of the
homes ventilation was below the requirements in building code
Renewable Energy and nZEB
developments in the HVAC sector seem toward the renewable supported mixed
systems. For such systems energy efficiency will be expected to reach 150%.
solar power production seems most promising renewable electricity production
system. There are many studies continuing on photovoltaic alone or hermetic
systems. Simultaneous power and thermal energy producing special vertical
sandwiching option of a PHVT module yields higher specific power outputs.
panels can be used to power the compressor of an inverter air conditioning
unit. This hybrid air conditioning unit simultaneously connected to grid and to
photovoltaic panels. This option is especially suitable for small
Refrigerant Flow systems bring opportunities to reducing CO2
emissions for hot water heating systems. Air to water VRF heat pump systems are
considered as renewable heat generators and their thermal efficiency values are
much higher than the conventional gas firing boilers. New generation VRF
systems can work efficiently even in cold winter conditions. Combining VRF with
the photovoltaic panels it was proved that net Zero Energy Building target can
be achieved. This was shown by the measured data of a case study in Germany.