THE INFLUENCE OF THERMAL ZONING on the THERMAL COMFORT and ENERGY CONSUMPTION in LOW ENERGY OFFICE BUILDINGS

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1 THE INFLUENCE OF THERMAL ZONING on the THERMAL COMFORT and ENERGY CONSUMPTION in LOW ENERGY OFFICE BUILDINGS Macedon MOLDOVAN, Ion VISA, Anca DUTA Renewable Energy Systems and Recycling R&D Center Transilvania University of Brasov, Eroilor 29, Brasov, Romania 45 th HVAC&R Congress and Exhibition, 3-5 December 2014, Belgrade, Serbia 1

2 GOAL The improvement of the thermal comfort and of the energy efficiency in low energy office buildings. 2

3 Outline Introduction Methodology Case study The RES REC Building of the R&D Institute of the Transilvania University of Brasov Results and Discussions Conclusions 3

4 WHY LOW ENERGY BUILDINGS? "Top Ten Problems of Humanity for Next 50 Years", Professor Richard Errett Smalley, Energy & Nanotechnology Conference, Rice University, May 3, Energy 2.Water 3.Food 4.Environment 5.Poverty 6.Terrorism & war 7.Disease 8.Education 9.Democracy 10.Population 1996 Nobel Prize laureate 4

5 WHY LOW ENERGY BUILDINGS? 10,000,000,000 in

6 WHY LOW ENERGY BUILDINGS? 10,000,000,000 in

7 WHY LOW ENERGY BUILDINGS? The new Recast of European Directive 2010/31/EU concerning the Energy Performance of Buildings (EPBD) Nearly Zero Energy Building mandatory Standard: 'very low energy needs all energy consumption inside the building, related to heating, cooling, ventilation and lighting meet those needs 'to a very large extent' by renewable energy, the renewable energy is 'harvested locally or in close proximity to the building'. In force for EU member states starting with: 2019 Public buildings new or existent buildings undergoing major renovation 2021 All buildings Barriers: - additional costs for improving the energy efficiency - additional costs for implementing the renewable energy systems - space availability for RES implementation 7

8 LOW ENERGY BUILDINGS (LEB) To obtain a LEB: an integrated design should be applied from the very first steps including: - passive design principles - energy savings measures - energy efficient equipment Objectives: - thermal comfort improved occupants satisfaction/productivity - reduced energy consumption for heating, cooling and lighting Thermal zoning: - represents a viable solution to address above objectives - through selective/differential heating or cooling. 8

9 WHY OFFICE BUILDINGS? EU BUILDING SECTOR 40% ENERGY CONSUMPTION AND ASSOCIATED GHG EMMISIONS NON RESIDENTIAL BUILDING REPRESENTS 25% OF BUILDING SECTOR OUT OF WHICH OFFICES + EDUCATIONAL = 40% 9

10 WHY OFFICE BUILDINGS? Because of the willingness of companies to invest to: - decrease theirs operating costs, - improve employees productivity, - improve its green image, as an open commitment towards sustainability. 10

11 WHY OFFICE BUILDINGS? SPECIFIC DESIGN CRITERIA a) large open offices, with a high ratio of glazed to opaque facades; b) FUNCTIONAL ZONES in which the office building is divided; c) floor position on the building height; d) the daily schedule, the occupancy; e) air pollution and odour control etc. 11

12 METHODOLOGY The paper proposes a novel concept of THERMAL ZONING. The concept addresses the second step of an algorithm* previously developed in general terms to improve the renewable energy mix for a building toward the nzeb status. * Visa I., Moldovan M.D., Comsit M., Duta A., Improving the renewable energy mix in a building toward the nearly zero energy status, Energy and Buildings, 68, 2014, Pg

13 METHODOLOGY THERMAL ZONING shall allow to differently heat/cool any floor of a building or any zone within a floor or a open space, according to their energy demand. The concept is based on the correlation between the variation in the air temperature throughout the open office surface and the heating / cooling demand, Aim: optimizing the design of the hydronic zones and theirs commissioning. Validation: indoor air temperature survey conducted in 2014 for an open office located in an office building in the new R&D Institute at Transilvania University of Brasov, Romania. Relevant data were selected and are discussed in the paper, outlining the importance of the outdoor solar radiation as input parameter, both during the heating and the cooling seasons. 13

14 ROMANIA / BRASOV CASE STUDY L7 ICDT temperate continental climate average summer temperature +20 C average winter temperature -4 C BRASOV BRASOV 500m above the sea level mountain area frequent temperature inversions heating design temperature -21 C cooling design temperature +27 C 14

15 CASE STUDY L7 ICDT R&D Institute of the Transilvania University of Brasov 11 OFFICE BUILDINGS 9 x 3kW SOLAR THERMA SYSTEMS 27 kw PHOTOVOLTAIC SYSTEMS 2 x 22 kw HEAT PUMPS 3 x 300W + 3 x 600W WIND TURBINES L7 15

16 CASE STUDY L7 ICDT L7 Building in the R&D Institute Transilvania University of Brasov, Romania, 45 40'08.6"N, 25 32'57.8"E Total surface area: 1350 m 2 Status: Low Energy Building 16

17 The L7 RES REC Office Building VERTICAL SECTION THROUGH RES REC BUILDING HORIZONTAL SECTION THROUGH THE FIRST FLOOR 17

18 Indoor Monitoring System 35 x EBI 25 TH SENSORS 3 x EBI 400 IF WIRELESS INTERFACES 18

19 Indoor Monitoring System Winlog.web monitoring software 19

20 Outdoor Monitoring System KIPP&ZONEN SOLYS 2 Sun Tracker Delta T weather station 20

21 RESULTS AND DISCUSSIONS Sunny day heating season all indoor sensors G H =global horizontal solar radiation, w=wind speed, t o =outdoor air temperature, t D =indoor design temperature and t i =indoor temperature sensors 21

22 RESULTS AND DISCUSSIONS Sunny day heating season only 4 indoor sensors G H =global horizontal solar radiation, w=wind speed, t o =outdoor air temperature, t D =indoor design temperature and T SE,SW,NW,NE =indoor temperature sensors 22

23 RESULTS AND DISCUSSIONS Cloudy day heating season all indoor sensors G H =global horizontal solar radiation, w=wind speed, t o =outdoor air temperature, t D =indoor design temperature and t i =indoor temperature sensors 23

24 RESULTS AND DISCUSSIONS Sunny day cooling season all indoor sensors G H =global horizontal solar radiation, w=wind speed, t o =outdoor air temperature, t D =indoor design temperature and t i =indoor temperature sensors 24

25 RESULTS AND DISCUSSIONS Sunny day cooling season only 4 indoor sensors G H =global horizontal solar radiation, w=wind speed, t o =outdoor air temperature, t D =indoor design temperature and T SE,SW,NW,NE =indoor temperature sensors 25

26 RESULTS AND DISCUSSIONS Cloudy day cooling season all indoor sensors G H =global horizontal solar radiation, w=wind speed, t o =outdoor air temperature, t D =indoor design temperature and t i =indoor temperature sensors 26

27 FUTURE DEVELOPMENTS MODELLING OF: 1. the influence of the solar radiation on the air temperature distribution in the open space; 2. the influence of the arrangement and commissioning of the hydronic on the air temperature distribution in the open space; TO ESTABLISH AN ALGORITHM FOR THERMAL ZONING 27

28 Conclusions 1. High indoor temperature differences (up to 8 C) between different peripheral zones during sunny days, both in the heating and in the cooling seasons!!! main causes: large open office with large curtain walls facing South; heating/cooling evenly distributed over the entire room (usual approach); consequences thermal discomfort; energy looses, especially in heating season through windows opening. 2. Possible actions aiming at increasing the thermal comfort and energy efficiency: interruption of the thermal energy supply where solar energy contributes to heating; fine tuning of the thermal energy flow through respective zones. 3. Thermal zoning is necessary: adequately positioning of the hydronic into the building thermally activated systems, in correlation with the building implementation site, orientation & envelope elements adequately commissioning of the hydronic in correlation with indoor & outdoor factors 28

29 Thank you! Acknowledgement: This paper is supported by the Sectoral Operational Programme Human Resources Development (SOP HRD), financed from the European Social Fund and by the Romanian Government under the project number POSDRU/159/1.5/S/