REHVA Journal – December 2012
Zoltán Magyar, PhD
Head of HVAC Department
University of Pecs, Hungary
According to the Hungarian decrees (7/2006 TNM and 40/2012 BM) in case of substantially renovated buildings, the specifications given for the doors and windows, slabs, walls, and floors have to be met, besides, the overall energy characteristics of the building must be below the specified value. The required figures of overall energy characteristics are specified for residential and accommodation-type buildings, office blocks, and educational buildings; buildings of other purposes belong to “other” category. There are no specific requirements for healthcare facilities, thus, the energy consumption of healthcare institutions, and the energy characteristics of some specific buildings of this type have to be surveyed by taking the requirements of the relevant Hungarian decrees into consideration.
The procedure of preparing an energy audit and assessment
The procedure includes the following:
· establishment of the requirements;
· identification of energy-consuming systems;
· establishment of actual energy consumption;
· comparison of actual energy consumption and the designed figures;
· proposing energy-saving measures.
The tasks of energy audits and assessment do not include exact cost-and-return-on-investment calculations since they would require asking for quotations, which belongs to the scope of feasibility studies. However, all energy audits are required to include calculations with at least approximate precision which help the owners or decision-makers decide which investments to launch or else which investments require the accomplishment of feasibility studies.
The aim of energy audits, therefore, is to
survey the energy consumption of the buildings concerned, and proposing
energy-saving initiatives for refurbishment. However, as it is specified in EU
directives, indoor environmental requirements have to be taken into
consideration for energy-saving measures. Concerning the air supply of
healthcare institutions, the Hungarian standard is suggested by MSZ 03-190:1987
can be taken
into account. In case of and public spaces and offices, the CEN report CR 1752
and standard EN 15251 are applicable.
As for the institutions surveyed, energy assessment has been carried out according to the following steps:
1. Identification of the buildings to be surveyed within the scope of the audit. Establishing the internal requirements (according to the data available or the function of the premises concerned).
2. Collecting the design documentation available (architectural and engineering implementation-plans, implementation plans of electrical network designs, technical specifications etc.).
3. Identification of power-supply systems, and areas of consumption. Clarification of the site-plan.
4. Collecting the utility and maintenance contracts, data of energy consumption (settling bills) concerning the previous 3 years.
5. Preliminary site survey, discussions with building operators and technical staff, recording operating experience.
6. Establishing actual consumption data according to the available bills. Analysis of consumption data, determination of average energy-consumption characteristics by taking heating degree-days into consideration, assessment of committed quantities. Analysis of energy cost, establishment of the actual-consumption-dependent and independent cost proportions.
7. On-site survey of building envelop and the associated HVAC and lighting-technology systems, field measurements (parameters of indoor climate, circulation time of DHW).
8. Assessment and summary of the results of the on-site measurements.
9. Heating-technology sizing of the buildings, according to the actual function of the premises (rooms), the current internal environmental requirements, and the current status of the building structure.
10. Determining the actual primary energy demand of the HVAC systems.
11. Comparison of the actual and design figures, exploring the reasons for any differences.
12. Proposing energy-saving measures. Assessment of the energy impact of the proposed initiatives according to the expected changes in specific heat loss figures, and the primary energy demand of HVAC and lighting-technology systems.
13. Analysis of payback times according to specific investment costs.
Evaluation of energy saving measures
The heating-technology sizing for the individual buildings and the establishment of primary energy demand of HVAC systems, and the analyses of the energy impacts of energy-saving measures have been carried out by means of the Hungarian WinWatt design software.
We have elaborated the energy-saving measures concerning building-structure renovation, and modernisation of HVAC systems and the electric network. The building-structure refurbishment in general includes the replacement or modernisation of doors and windows, and the external thermal-insulation of the building concerned.
Modernisation of the heating system, by all means, shall include the replacement or renovation of outdated heating systems, hydronic balancing, installation of radiators with thermostatic valves.
Concerning water supply, by installing water-saving faucets, toilet tanks, and urinal rinse tanks, the amount of water used and thus the total operation costs can be reduced. In case of healthcare facilities, prevention of legionella infection is particularly important. This can be achieved by providing sufficient DHW, and establishing suitable hot-water systems (by the elimination of stagnant water-line sections, and providing satisfactory circulation).
The modernisation of electric networks includes the replacement of the existing lighting system with energy-saving alternatives. When replacing the fluorescent lamps, the transition to modern electrical ballasts is also advisable. Additional savings can be realised by installing motion-detector lighting design, where it seems appropriate. It is generally recommended to check the efficiency of the electric-power-consuming machinery and equipment, and to replace the outdated ones. Thereby inductive idle power is also going to be reduced, implying further cost saving. A further option, in order to reduce reactive performance, is offered by installing multiple power factor correction units. In this case, the instrumental analysis of the impact of the performance to be compensated to the network, and, if necessary the installation of filter-circle power factor correction units are recommended.
In addition to the above, in order to rationalise energy consumption, it is always recommended to provide energy training to the staff, users and operator in order to realise energy-conscious behaviour.
Technical systems in case buildings
In case of the institutions involved in the study, a total of 18 buildings and the related HVAC systems and lighting systems have been assessed, predominantly according to their primary energy consumption. The buildings are located in Hungary, Gyor  and Derecske .
The structure of the dominantly brick-masonry buildings were seriously deteriorated. With the exception of some buildings no significant renovations have been completed, only on-going repairs and facade renovations have been implemented. Consequently, in the majority of the buildings most of the problems have been implied by the outdated windows and roof structures. (In relation to this, in the buildings concerned draught problems have been experienced almost constantly.)
The heating and domestic hot water supply, with one exception, is provided by the district-heating network. Natural gas and steam are used for technological purposes only. The heat emitters of the buildings are usually cast-iron radiators, typically installed without thermostatic radiator valves. The pipe networks are of mixed design (one-pipe without bypass, one-pipe with bypass and two-pipe systems).
On the secondary side pumps with constant speed were installed. In many cases the control on the second side does not function adequately, therefore, manual control is applied. The hydronic balancing of the systems have not been accomplished, the relevant valves needed for it are missing. In several cases, technological heat usage is wasteful.
The faucets are traditional and
single-lever mixing design. The flush of the toilets are of mixed types; it is
either supplied by upper flushing tanks, or, in the renovated toilets, (about
15%) there are flushing tanks equipped with flush-stop function. Domestic hot
water is circulated in the majority of the buildings, however, according to users’
complaints, circulation is insufficient. This was justified by on-site
measurements as well. The electric systems of the buildings were installed
predominantly in the seventies, and they represent the technological standards
of the era concerned. The estimated average age of lighting systems can be
between 20‑30 years, in most cases they are outdated and fail to meet the
modern-day standards. In some specific buildings, energy-effective (and
reliable) operation is hindered by 20‑30-year-old distributor-fuse
equipment. Meanwhile, the gradual replacement of lighting units to modern
mirror-reflection energy-efficient versions began in the recent years.
Results of the energy audit and assessment
In the following the assessment of energy saving initiatives and their estimated effect are presented.
· Installation of thermostatic radiator valves and their adjustment.
· Replacement or modernisation (by replacing their seals and by applying the so-called Duplo-Duplex method) of doors and windows.
· Decrease of filtration by the alteration of internal space connections.
· Subsequent external thermal insulation (walls and slabs).
· Complete thermal insulation of the building (Subsequent external thermal insulation and replacement or modernisation of doors and windows.
· Complete thermal insulation of the building and modernisation of the heating system (exchange of radiators, installation of thermostatic radiator valves, balancing valves and balancing the heating system).
· Complete modernisation with individual gas boiler (total thermal insulation of the building and modernisation of the heating system, installation of individual gas boiler with control by outdoor temperature and variable speed pumps).
· Complete renovation with individual condensing gas boiler total thermal insulation of the building and modernisation of the heating system, installation of individual gas boiler with control by outdoor temperature and variable speed pumps).
Remark: In case of hospitals with
several pavilions this solution does not make management with state-of art
technology possible or the application of alternative fuels. It can be a good
solution in case of clinics.
Table 1 shows the actual energy consumption of different parts of the hospital. Based on the calculation different measures were suggested. The estimated reduced energy consumption in primary energy demand is presented in the Figure 1.
Table 1.The thermal energy use of buildings according to the survey.
Qtr [kW] = total heat loss of the building
qcalc [W/(m³K)] = calculated specific heat-loss coefficient
qall [W/(m³K)] = allowed value of specific heat-loss coefficient
qh [kWh/(m²a)] = net thermal-energy value of heating
Eh [kWh/(m²a)] = primary energy demand of the heating system
EDHW [kWh/(m²a)] = primary energy demand of the DHW system
Figure 1.The calculated impact of energy-saving measures on primary energy demand of heating systems.
The article presented the possible energy efficient refurbishment in Hungarian hospitals. The current energy consumption is show in the table. The effects of the energy saving options are presented in Figure 1. Based on this study the energy efficient refurbishment has started and will be completed soon. A few years later the real energy consumption will be compared with the calculated measures.
1. Feasibility Study on the Energy Refurbishment of the Premises of the City Council of Dereceske, Hungary; Comfort Consulting Ltd. 2007.
2. Feasibility Study on the Energy Refurbishment of AladarPetz County Hospital, Hungary, Comfort Consulting Ltd. 2007.
3. Kontra, J.: Experience Concerning Energy Reconstruction of Hospitals; Hungarian HVAC Magazine, Budapest, 2004.
4. Magyar,Z. - Leitner,A. - Berenyi, A.: Energy audit of Healthcare Institutions, Hungarian HVAC Magazine, Budapest, 2007.