REHVA Journal – August
Clemens Haury from the European Commission focused in his presentation on the main instruments of Energy efficiency policy and the priorities of future actions.
Professor Hiroshi Yoshino from Tohoku University, Japan, presented the summary of the IEA´s working group Annex 53 “Measured energy use in buildings and its break down” and pointed out how large variation in energy use can be due to the user. In the figure the variation electricity use of air conditioning in Chinese apartments.
Professor JarekKurnitski presented overview of net and nearly zero energy buildings and summary of the common technical features of nearly zero energy office buildings in northern and southern European conditions.
Donald Leeper from UK, emphasized in his presentation
the importance of energy certificates based on measured energy use (Display
Energy Certificate) widely used in UK. He also showed the benchmark values of
CO2 emissions in different types of buildings developed by the REHVA British
and the main conclusions of the conference
The main conclusion of the conference was that the low energy retrofitting of building is a huge challenge to the whole Europe, and the HVAC systems are a key contributor towards energy savings when the EU is to reach its target of reducing 20% the energy use by 2020.
The main topics of the conference were: how to improve the energy efficiency of the existing buildings, how to select the most cost effective methods to do it and how to motivate the building owners to implement the renovation of buildings.
Several presentations were focusing on the
recast Energy Performance of Buildings Directive (EPBD) which is the most
important piece of legislation to help to achieve this goal of energy
efficiency in the EU. Specifically, the introduction of “nearly zero-energy buildings” by 2021/2019
will create major changes in the building industry and construction practice
during the next decade. All member states will have to develop minimum energy
performance requirements to all buildings. Even there is no obligation to
renovate the existing buildings the regulations for the new buildings will
speed up also the refurbishment rate of the existing building stock.
strengthening of Energy Performance Certificates and Inspections is required
also in EPBD. This will require new legislation in many countries. The
requirement for guidance of the energy improvement measures as a part of energy
certificate requires qualified well trained inspectors. The training of the
inspectors is a huge challenge for the engineering community.
studies (like IEA Annex 53) showed how important the occupant behavior is when
evaluating the total energy use in buildings. The energy use of similar
apartments or houses may vary in the ratio 1:4 due to occupants´ behavior. This
needs much more attention in the future. It was also evident that office
appliances have become major component in the energy balance of office
European recast Energy Performance of Building Directive requires also the
inspection of air-conditioning and heating systems. The presentation at the
conference illustrated how the requirements in the directive can be implemented
and how the good results can be achieved. Monitoring of the energy use of the
building also revealed that the largest energy use in many office buildings is
not due to HVAC but many other services in building like food and computer
performance certificate (EPC) is required for all buildings. It is based on
calculation of energy use with standardized operation schedules. However,
buildings are never used exactly according to the predicted way.
benefits of energy certificates based on measured energy use were widely
discussed as they give also guidance to building owners regarding the need to
take action for operational improvements. In UK, the measured energy use is
used in the Display Energy Certificate (DEC) which is required parallel to EPC.
DEC shows the actual energy use of the building compared to typical energy use
of similar buildings of that type. It tells to building owner how effectively
the building is managed. It is a measure of real operational energy use. It is
based on energy use per unit area – quick and easy to measure and compared to
an EPC. In the long run both calculated and measured certificates are needed.
The importance of HVAC
technology in Energy retrofitting
ventilation and air condition systems play an important role when improving the
energy performance of buildings. The studies have shown that in central system
the balancing of the heating and improving the control system will bring
significant saving in heating and at the same time improve the indoor
environmental conditions. The following measures are particularly cost
effective when improving the energy efficacy of heating system:
of pipes of the heating and DHW distribution system
of the heat generator with a more efficient one (i.e. with a condensing boiler
or geothermal heat pump …)
of technologies that employ renewable energy sources (solar system, biomass …)
of the heating system to district heating network (if available)
efficient distribution networks (pumps)
and ductwork air leakage levels are reasonably well-known. It is also
recognizes that a lot can be done to reduce to energy losses through building
and duct leakage. Strict requirements for building and duct leakage should be
imposed in all climates. Improvement of building air tightness is relative easy
and cost effective, and professionals can rapidly integrate these issues in the
construction practice. Testing is easy and can be rapidly integrated in a
regulatory control schemes.
In the area
of energy efficient ventilation the following measures were agreed to be very
important in improving the energy efficiency:
Control the ventilation and air-conditioning
according to the use of the spaces and by installing demand controlled
ventilation systems. In commercial buildings, in particular, ventilation rate
should depend on level of occupancy. But also, in residential buildings
operation of HVAC system should depend on the time of day (at home, outside),
and room which are in actual use (living room, bedroom). Obvious need is for
more representative sensors and better control concepts.
of HVAC systems is important when reducing the energy use in buildings. The
cost of commissioning is between 0,3 % and 0,7 % of
the total development cost but the energy cost saving is between 5 % and 15 %.
As the result of commission the system performs better and benefits can be seen
such as: increased staff productivity lower maintenance costs and environmental
Nearly zero energy
EPBD requires all new building to be nearly zero energy buildings by 2021. Such
buildings have been already constructed. In general nearly zero energy building
energy demand + effective systems + on site renewables
technical features in nearly zero energy office buildings were reported to be:
efficient energy sources and renewables to be used:
heat pumps, DH, bio-CHP, solar PV and thermal
recovery ventilation; often demand controlled, by centralized or decentralized
systems sometimes combined with natural stack effect ventilation for ventilative cooling purposes
cooling solutions combined with mechanical cooling via boreholes, water to
water HP, evaporative or ventilative cooling etc.
building envelope and effective external solar protection
of natural light + effective demand controlled lighting
efficiency heat recovery and low specific fan power;
CO2, presence and temperature control systems
based distribution systems and VRV heat pumps
of thermal mass and other passive measures
opinion of the conference participants was that in many cases the installation
of heat pumps is a cost effective way to reduce primary energy use of
buildings, particularly if the building has direct electrical heating.
REHVA activities for
REHVA – the
Federation of European HVAC Associations has the improvement of energy
efficiency of building in its agenda, and as an important part of its strategy.
REHVA has several activities to help the members in implementing energy
efficiency of buildings.
published two new guidebooks at its annual meeting, both helping building owner
to make the building more energy efficient. These are:
Guidebook 16: HVAC in Sustainable Office Buildings - A bridge between owners
and engineers was created for building a bridge between the real estate
community and the engineering community.
Guidebook 17: The Design of energy efficient ventilation and air-conditioning
also several Task Forces developing new Guidebooks related to the energy
efficiency of buildings such as:
REHVA Task Force on NZEB lead by prof. JarekKurnitski continues its
work for better definition on nearly zero energy buildings.
Task Force lead by prof. MarijaTodorovic is planning to publish three REHVA
Guidebooks on the Energy retrofitting of the building in the near future.
On the EU level REHVA has supported the Commission when new
regulations and directives are being developed. REHVA supports the ideas in the
original Energy Efficiency Directive from the Commission with its target
renovation rates, and binding requirements for the reduction of energy use and
the leading role of the public sector. REHVA has also emphasized the fact that
buildings are for people, and the first objective is to maintain in buildings
good, healthy indoor environment, and that this target cannot be sacrificed
when implementing energy efficiency improvements.