Optimizing Existing Multistory Building Designs towards Net ... - MDPI

sustainability Article

Optimizing Existing Multistory Building Designs towards Net-Zero Energy Mohammad Y. AbuGrain and Halil Z. Alibaba * Department of Architecture, Faculty of Architecture, Eastern Mediterranean University, North Cyprus, Famagusta, Mersin 10, Turkey; [email protected] * Correspondence: [email protected]; Tel.: +90-533-863-0881; Fax: +90-392-630-2365 Academic Editors: Andy van den Dobbelsteen and Greg Keeffe Received: 14 December 2016; Accepted: 1 March 2017; Published: 8 March 2017

Abstract: Recent global developments in awareness and concerns about environmental problems have led to reconsidering built environment approaches and construction techniques. One of the alternatives is the principle of low/zero-energy buildings. This study investigates the potentials of energy savings in an existing multi-story building in the Mediterranean region in order to achieve net-zero energy as a solution to increasing fossil fuel prices. The Colored building at the Faculty of Architecture, Eastern Mediterranean University, Cyprus was chosen as a target of this study to be investigated and analyzed in order to know how energy efficiency strategies could be applied to the building to reduce annual energy consumption. Since this research objective is to develop a strategy to achieve net-zero energy in existing buildings, case study and problem solving methodologies were applied in this research in order to evaluate the building design in a qualitative manner through observations, in addition to a quantitative method through an energy modeling simulation to achieve desirable results which address the problems. After optimizing the building energy performance, an alternative energy simulation was made of the building in order to make an energy comparison analysis, which leads to reliable conclusions. These methodologies and the strategies used in this research can be applied to similar buildings in order to achieve net-zero energy goals. Keywords: net-zero energy buildings; existing buildings; energy efficiency strategies; energy modeling simulation

1. Introduction Cyprus, one of the largest islands in the Mediterranean has no petroleum reserves and is completely dependent on imported energy from petroleum products. The energy statistics of North Cyprus over the past 20 years show high increases in annual electricity consumption, and all sectors energy is being provided from Cyprus Turkish Electricity Authority (KIB-TEK) which is being put under oppressive pressure by customers who call for maximize the suppling capacity, which is costly due to the high price of fossil fuel [1]. This uncertain load increase and the rising cost of fossil fuels, requires serious attention and consideration specially to buildings optimizations towards sustainability and energy efficiency [2]. Worldwide, existing buildings consumes around 40% of end use energy however 1%–3% annually of these buildings are being replaced by new-build [3–5]. Thus, reducing domestic energy consumption and integrating renewable energy sources for energy savings has become an international trend as a strategy for reducing the level of peak demand from the electricity grid. Therefore, energy efficiency in buildings and net-zero energy buildings (NZEB) concepts have attracted intense attention from researchers, architects, and engineers. NZEB refers to a building consuming equal (or less) energy than what it produces within a single year. The idea of starting a time-period assessment for NZEB that refers to a yearly basis is critical,

Sustainability 2017, 9, 399; doi:10.3390/su9030399

www.mdpi.com/journal/sustainability

Sustainability 2017, 9, 399

2 of 15

so as to allow variations in different seasons of the year. Therefore, the highest amount of energy needs in the winter (due to lower sun gains) for heating can be balanced at the end of year by energy delivered from renewable energy sources during the summer [6]. There are many definitions for NZEB; it depends on the specific goal of the project and the different points of views of the owners and the design team, the economic issues, and energy costs that are more important for the owners. However, the national energy members are interested in renewable sources of energy, and designers are more interested in requirements and energy codes [7]. As a general definition, net-zero energy (NZE) is the annual energy balance between the operation/demanded energy and the generated energy from the renewable sources [8], and a net-zero energy building (NZEB) is a building that produces enough energy to sustain itself. Considering NZEB concept into renovating public building maximize the energy efficiency in existing building, in addition, since exiting buildings will last for more decades, optimizing towards NZE also share in the sustainable urban development. Nowadays, various countries are trying to approach net-zero energy concepts in their buildings and are planning to achieve this goal within a certain time. The European Union (EU) Energy Performance of Buildings Directive (EPBD) stated in their official journal that all new buildings in European countries should be NZEB by the end of 2020 [9]. Regardless of the new construction, existing buildings are the largest energy consumers which are still operating, but require renovating in order to decrease their energy needs; hence, EPBD set the existing and public buildings as a starting target in European countries [10,11]. Many guidelines for early design stages have been set in order to achieve this goal for new construction [12]; different strategies and frameworks have been provided to achieve desirable results in existing buildings [13] and there are many examples of retrofit projects that achieve this goal. However, each project applies different strategies according to its type, local climate, and other measurements. Winter represents the peak energy demand load curve in North Cyprus, which is basically consumed by residential sector [14] according to the working hours. Statics shows if 5% of the existing residential buildings implement stand-alone renewable energy production system, this will lead to 4% decrease in the peak demand [1]. In terms of public buildings, main operating schedules is during the day time, where the maximum benefits can be get from photovoltaics to provide demanded energy. As such, it is important to regenerate the design of existing buildings and develop strategies towards the zero energy concepts in N. Cyprus. The studies towards NZEB stated in the literature are only for designing new buildings or existing two-story residential buildings [15–17]. Thus, this study focuses on how well public buildings in North Cyprus meet the Energy Performance of Building Directive (EPBD) stated goals for 2020. For this purpose, a typical building located at the Eastern Mediterranean University (EMU) Faculty of Architecture is chosen as a case study. 2. Literature Review According to Professor François Grade’s research about NZEB design [17], there are two major factors that must be considered and analyzed in the early design phases to achieve NZEB targets: (1) (2)

Optimizing the passive solar energy concepts to reduce building energy consumption, and Generate sufficient electrical energy by renewable energy sources to reach energy balance.

Integration of passive techniques acts as a critical apparatus towards zero energy building design goals. It has direct influences on thermal balance and lighting loads, which affects the electro-mechanical systems of the building. This creates a noticeable indirect reduction in heating/cooling, lighting, and ventilation energy consumption that is sufficiently balanced by renewable energy systems [17]. Since implementing the passive solar energy in the building influences the loads in the electro-mechanic system, passive strategies takes a vital position in NZEB design. Studies proved that efficient integrating of passive shading controls in the building envelope and building elements

Sustainability 2017, 9, 399

3 of 15

dramatically reduce the annual lighting energy demand by 40%, and this percentage increases to 60% if automated shading device have been integrated [18]. Moreover, effective controlling of daylight can reduce 10%–20% of the annual cooling/heating energy demand [18]. Furthermore, it indirectly affects challenges facing energy produced by renewable resources. In general, the consideration of optimizing passive heating and cooling strategies are combined together in order to prevent glare by direct sunlight and overheating in cooler seasons. In addition, the thermal mass of the building provides a method to achieve passive cooling, which significantly reduces the cooling loads [19,20] for taking advantage of daylight and natural ventilation. Meanwhile, in hot seasons, distinguished by the use of the fresh air and the building’s loss heat at night it is the non-use of the walls’ thermal insulation that prevents heat loss during night time. The appliance of passive strategies constitutes many challenges correlated to the building type, climatic conditions, CO2 emission levels, and optimum energy performance, consequently, by collaborative research with the Solar XXI project, built in 2006 at LNEG Campus in Lisbon [21], which claims to be an example of a low solar energy building integrating inert strategies for heating and geo-cooling systems to achieve NZEB [22]. Photovoltaic panels are integrated in the facade design with a heating system for thermal balance in winter. Otherwise, a geo-cooling system (ground tubes) assisted by night cooling approaches work together to cool the building in summer. Furthermore, opening sizes and glazing specifications in the facade has a direct influence on the indoor thermal comfort in warm climate conditions [23], which affects the cooling and heating loads, and on the use of daylight which affects the lighting loads [24]. In terms of the ventilation impact on building energy consumption, recent research using for dynamic thermal simulations EDSL Tas software found the percentage of the window openings’ influence on the thermal comfort and energy consumption for cooling and heating for different seasons in a hot and humid climate [25]. These results found that lowering the window to wall ratio (WWR) decreased the energy consumption and a large WWR increases energy consumption. However, a large WWR increases energy consumption in all climates [26], the small WWR affects the daylighting efficiency [27], and lighting consumption can be managed by using controllable electric lighting systems and optimum shading devices, especially for large glazing sizes [28]. However, energy consumed, in this case by HVAC systems for heating and cooling, must kept in mind. The U-value and G-value of the glass are important factors in terms of cooling and heating energy consumption, and lowering the U-value respectively decreases the energy consumption for different WWR and increases the energy efficiency of the building [29]. Most of NZEBs in research projects apply yearly balance to support their used methods [30], and the same concept is applied in this paper to investigate optimizing public building towards net zero energy. The methodologies and the case study building will be described in the following sections, along with the findings of the observations and computer simulations, and a discussion about the suitable design optimizations and potential for achieving net-zero energy in the building. 3. Methodology Case study problem solving, and surveying methodologies will be used in this research in order to reach conclusions. Firstly, the building has been surveyed and analyzed through observation, which is presented via photos and computer simulations via Autodesk Ecotect analysis [31] to find and define the problems statistically. The data will be analyzed using both qualitative and quantitative methods to accurately determine the energy problems. Secondly, an energy optimization of these problems has been done through an energy modeling simulation (eQuest energy simulation tool [32].) based on interviews managed with expert architects in energy efficient buildings and renewable energy technologies, in addition to the passive optimization principles found in the literature. Finally, the energy simulation results after optimization are discussed to make an energy comparison of existing situation and alternatives energy savings to help develop the strategy of achieving net-zero energy use in the case study. The case study is located in Cyprus-Famagusta, one of the largest islands in the Mediterranean Sea (35◦ Latitude, 33◦ Longitude). With a humid-hot climate, the temperature rises above 30 ◦ C in the

Sustainability 2017, 9, 399 Sustainability 2017, 9, 399

4 of 15 4 of 15

hottest months during duringthe thetypical typical summer season, temperature decreases to in 3 the °C winter in the hottest months summer season, andand the the temperature decreases to 3 ◦ C winter 1), as in stated in the Cyprus meteorological reportFamagusta about Famagusta season season (Figure(Figure 1), as stated the Cyprus meteorological station station report about [33]. [33]. According location, Famagusta hassolar high solar energy during(5.26 thekWh/m winter2 /day), (5.26 According totoitsits location, Famagusta has high energy during the winter 2 2 2 kWh/m /day), which rises to/day 7.12 kWh/m /day duringseason. the summer season. which rises to 7.12 kWh/m during the summer

Figure Figure 1. 1. The The annual annual graph graph of of Famagusta’s Famagusta’s climate climate [34]. [34].

3.1. 3.1. Case Case Study: Study: Observation Observation Findings Findings and and Analysis Analysis The The Colored Colored Building Building is is an an educational educational building building with with aa rectangular rectangular shape shapeand andhas hasthree three floors, floors, containing a library and a seminar room, and most of spaces are studios for architectural students. containing a library and a seminar room, and most of spaces are studios for architectural students. The The building building is is oriented oriented 31° 31◦ to to the the north north and and 59° 59◦ to to the the east. east. As shown in Tables 1–5, through description of designdesign elements, as in theasFigures As shown in Tables 1–5, through descriptionthe of case the study case study elements, in the 2–6, the evaluation is based on NZEB design strategies in the literature review and elements that Figures 2–6, the evaluation is based on NZEB design strategies in the literature review and elements affect the energy efficiency of the building. that affect the energy efficiency of the building. Table Table 1. 1. Analysis Analysis of of the the northwest northwest facade facade of of the the case case study. study. Observed Facts Facts The Colored Observed Building elevations have the Thesame Colored Building elevations have thewith same treatments facing all directions, treatments facing all directions, with large large parts of windows, and no shadingparts of windows, andbeen no shading been devices have used ondevices exteriorhave facades. used on exterior facades.

Author Evaluation Author Evaluation The large windows increase interior The large windows increase interior daylighting daylighting efficiency, though this causes efficiency, though this causes overheating overheating in summer, which leads to an in summer,inwhich leads to andemand increase[26]. in cooling increase cooling energy energy demand [26].

Sustainability 2017, 2017, 9, 9, 399 399 Sustainability Sustainability 2017, 9, 399

of 15 15 55 of 5 of 15

Figure 2. 2. Northwest of the the case study study building. Figure Northwest facade facade of Figure 2. Northwest facade of the case case study building. building.

Figure 3. 3. Southwest Southwest facade facade of of the the case case study. study. Figure Figure 3. Southwest facade of the case study.

1.

2.

Table 2. Analysis of Table 2. Analysis of the the southwest southwest facade facade of of the the case case study. study. Table 2. Analysis of the southwest facade of the case study. Observed Author Observed Facts Facts AuthorEvaluation Evaluation Observed Facts Author Evaluation 1 The building is surrounding by trees at the 1 The building is surrounding by trees at the The building is surrounding by trees at the which southeast and southwest elevations, This causes overheating in and southwest elevations, which southeastsoutheast and southwest elevations, which drops some shade on parts of the building. This causes overheating in the summer, which increase drops some shade on parts of the building. drops shadeatonmidday parts ofonthe 2 some Though, thebuilding. facades that face Thisthe summer, which increase causes overheating in the summer, the cooling energy demand. 2 Though, at midday on the facades that face the sun direction, radiation shines vertically cooling demand. whichthe increase theenergy cooling energy demand. the sun direction, radiation shines vertically Though, on at midday on the facades that face the glazing parts. on glazing parts. sun direction, radiation shines vertically on glazing parts.

Sustainability 2017, 9, 399 Sustainability 2017, 9, 399

6 of 15 6 of 15

Sustainability 2017, 9, 399

6 of 15

Figure 4. Typical studio interior interior view. view. Figure 4. Typical studio Table 3. 3. Analysis Analysis of of aa typical typical interior interior view view of of the the studio. studio. Table

ObservedFigure Facts4. Typical studio interior view. Author Evaluation Observed Facts Author Evaluation Typical interior window blinds are being used for These is insufficient shading Tableinternally 3. Analysis of a typical interior view of because the studio.they obstruct daylight studios’ windows due to the lack of 1. theTypical interior window blinds are being used for theshading studios’ devices windows to the from exterior tointernally protect due the users and the visual efficiency of Observed Facts Author Evaluation These is insufficient shading because lack of exterior shading devices to protect the and glare. users, increasing the daylight andshading thelighting visual 1overheating Typical interior window blinds are being used forthey obstruct These is insufficient users from overheating and glare. of users, increasing the the studios’ windows internally due to the lack because they obstruct daylight demand [18]. 2 Artificial lighting is being used during day.ofefficiency 1

2. 2

[18]. exterior shading devices to protect the users fromlighting anddemand the visual efficiency of Artificial lighting is being used during the day. overheating and glare. users, increasing Table 4. Analysis of internal view of the atrium and corridors.the lighting demand [18]. Artificial lighting is being used during the day.

Observed Facts Author Evaluation Table 4. Analysis of internal view of the atrium and corridors. Tablein 4. the Analysis of internal the atrium and corridors. A large skylight is placed atrium of theview of This insufficient usage of artificial lighting building to provideObserved enough daylight to corridors increases lighting energy consumption Observed Facts Author Evaluation Facts Author Evaluation and inside deep spaces, though lamps are being and causes overheating of the atrium AA large skylight is isplaced This insufficient usage of artificial lighting and large skylight placedininthe theatrium atriumofofthe This insufficient usage of artificial lighting usedbuilding during the day. corridors during the summer. to provide enough daylight to corridors increases lighting energy consumption the building to provide enough daylight to increases lighting energy consumption and and inside deep spaces,deep though lamps are being causes and overheating causes overheating of the and atrium and corridors and inside spaces, though of the atrium used during the day. corridors during summer. lamps are being used during the day. corridors during thethe summer.

Figure 5. Internal view of atrium and corridors. Figure 5.5.Internal of atrium atriumand andcorridors. corridors. Figure Internalview view of

Sustainability 2017, 9, 399

7 of 15

Sustainability 2017, 9, 399

7 of 15

Sustainability 2017, 9, 399

7 of 15

(a)

(b)

Figure 6. (a) Northeast façade; and (b) internal view from the northeast facade.

Figure 6. (a) Northeast façade; and (b) internal view from the northeast facade. Table 5. Analysis of the facade construction material.

Table 5. Analysis of the facade construction material. (b) Evaluation Observed (a) Facts Author 1

Typical window materials are made of single Poor view insulation of windows in this building Figure 6. (a) Northeast façade; and (b) internal from Author the northeast facade. Observed Facts Evaluation clear 4 mm thickness glass, with PVC frames. negatively influence the level of heating loss during Typical window made of of single winter and heating gain during summer, which 2 1. Walls are made outmaterials of 20 cm are thick red brick. Table 5. Analysis the facade construction material. Poor insulation of windows in this building mm thickness glass, are withbeing PVCused. frames. increase theinfluence cooling/heating energy demand. 3 Noclear extra4 insulation materials negatively the level of heating loss Observed Facts Author Evaluation during winter and heating gain during summer, Walls are made materials out of 20 cm brick. 12. Typical window are thick madered of single Poor insulation of windows in this building which increase the cooling/heating 3.2. Case Study: Simulation Findings and Analysis clear 4 mm thickness glass, with PVC frames. negatively influence the level of heating loss during energy demand. 3. No extra insulation materials are being used. winter and the heating during which via 2 AsWalls made out ofbefore 20 cm thick redMethodology brick. it hasare been stated in the section, casegain study hassummer, been analyzed increase energy demand. 3 No extra insulation are being used. according computer software toolsmaterials (Autodesk Ecotect) tothe itscooling/heating original orientation and weather

3.2. Case Study: By Simulation and envelope Analysis parameters and material specifications and glazing conditions. entering Findings the building 3.2. Case Study: Simulation and Analysis transparency, the programFindings can analyze the inputs and provide accurate data on an annual basis

As it has been stated before in the Methodology section, the case study has been analyzed whichAs helps to evaluate different design elements that the influence the energy efficiency ofvia the it has been stated before passive in the Methodology section, case study has been analyzed via computer software tools (Autodesk Ecotect) according to its original orientation and weather building. computer software tools (Autodesk Ecotect) according to its original orientation and weather conditions. entering thethe building parameters and material specifications andand glazing TheBy analysis of daylighting has envelope been conducted according to the sunspecifications path during the conditions. By entering building envelope parameters and material andyear glazing transparency, the program can of analyze the inputs provide accurate data onon ananannual basis the transmittance sizes theanalyze windows alland orientations. Theaccurate results show more than 1100 luxwhich transparency, theand program can theininputs and provide data annual basis helpsilluminance to evaluate design elements thatyellow influence the energy efficiency of the building. in the interior spaces,elements the range shows a high level above which helpsofdifferent todaylighting evaluatepassive different passive design thatcolor influence the energy efficiency of the building. that required, of as daylighting seen in Figure due to the lack of exterior shading devices, ofyear the and The analysis has7 been conducted according to the sun path especially during the The analysis of daylighting has been conducted according to the sun path during the year and southwest facade, which faces the most sun radiation during the summer season and causes the transmittance and sizes of the windows in all orientations. The results show more than 1100 lux the transmittance and sizes of interior the windows in all orientations. Therange resultsshows show more than 1100 lux that overheating to the interior illuminance of daylighting in spaces. the spaces, the yellow color a high level above illuminance of daylighting in the interior spaces, the yellow color range shows a high level above required, as seen in Figure 7 due to the lack of exterior shading devices, especially of the southwest that required, as seen in Figure 7 due to the lack of exterior shading devices, especially of the facade,southwest which faces the most sun radiation during the summer season and causes overheating to the facade, which faces the most sun radiation during the summer season and causes interior spaces. overheating to the interior spaces.

Figure 7. Daylight analysis of typical floors (first and second floors) of the case study.

Figure 7. Daylight analysis of typical floors (first and second floors) of the case study.

Figure 7. Daylight analysis of typical floors (first and second floors) of the case study.

Sustainability 2017, 9, 399

Sustainability 2017, 9, 399

8 of 15

8 of 15

The skylight in the atrium provides acceptable daylight levels (red colour range) to the deep spaces inThe theskylight buildinginsuch as the corridors during thedaylight day. Onlevels an annually basis, this shows that the the atrium provides acceptable (red colour range) to the deep artificial not required the day. spaceslights in theare building such as during the corridors during the day. On an annually basis, this shows that the In terms of the interior environment, an annual basis, Figure 8 shows hourly temperatures artificial lights are not required during theon day. which are examined to define the temperature variable between the interior These are In terms of the interior environment, on an annual basis, seasons Figure 8inshows hourlyspaces. temperatures usedwhich to calculate the cooling/heating load demanded that provides thermal comfort forspaces. occupants, are examined to define the temperature variable between seasons in the interior Theseand are usedthe to total calculate the cooling/heating demanded that provides thermal comfort for determines heat gain according to theload building construction materials (walls and windows). occupants, and determines the total heat gain according to the building construction materials (walls The results are as follow: and windows). The results are as follow:

(1)

From November to March (winter season): the average internal temperature is between 8 ◦ C and

(1) ◦From November to March (winter season): the average internal temperature is between 8 °C 15 and C. 15 ° C. (2) (2)From April to October (summer season): the average of internal temperature increases to between From April to October (summer season): the average of internal temperature increases to ◦ ◦ 20 between C and 33 C. and 33 °C. 20 °C

Figure 8. 8. Hourly duringthe theyear. year. During the winter; and (B) during Figure Hourlytemperature temperature analysis analysis during (A)(A) During the winter; and (B) during the the summer. summer.

Sustainability 2017, 9, 399

9 of 15

Accordingly, electric energy demand for heating/cooling increases due to the following building envelope solar gain breakdown chart, as seen in Figure 9, which shows where the heat loss or gain coming from: Sustainability 2017, 9, 399

•

• • • •

9 of 15

About 60% (red color) of the building thermal loss in winter is caused by material conductivity Accordingly, electric energy demand for heating/cooling increases due to the following building because of gain the breakdown poor thermal while9,just 7%shows of thewhere totalthe gain from the same factor envelope solar chart,insulation as seen in Figure which heatisloss or gain in summer. coming from: gain is of from sol-air thermal (brownlosscolor) because ofbythe monocular heating of the  About About 12% 60% (red color) the building in winter is caused material conductivity building material. because of the poor thermal insulation while just 7% of the total gain is from the same factor in summer. Direct solar radiation (yellow color) is responsible for 38% of heat gain through the year because  ofAbout 12%ofgain is fromshading sol-air (brown color) because of the monocular heating of the building the lack exterior and the windows transparency. material. Opening sizes, which have a direct impact on ventilation, are major factors causing a 26% drop  Direct solar radiation (yellow color) is responsible for 38% of heat gain through the year (green color) total thermalshading loss during winter. because of theinlack of exterior and thethe windows transparency.  About Opening which direct impact on (blue ventilation, major factors causingof a 26% 31%sizes, of gain is have fromainternal spaces color)are and a small amount gaindrop and loss is from (green color) in total thermal loss during the winter. the distribution between different spaces (inter-zonal indicator). 

About 31% of gain is from internal spaces (blue color) and a small amount of gain and loss is from the distribution between different spaces (inter-zonal indicator).

Figure 9. Yearly gains breakdown of the case study.

Figure 9. Yearly gains breakdown of the case study.

Sustainability 2017, 9, 399 Sustainability 2017, 9, 399

10 of 15

10 of 15

In addition to the previous data findings, an interview was organized with the technical office In addition to the previous data findings, an interview was organized with the technical office engineer at Eastern Mediterranean University to provide the technical data of the building. Taking engineer at Eastern Mediterranean University to provide the technical data of the building. Taking into into consideration the internal loads and operating timetables, artificial light efficiency, in addition consideration the internal loads and operating timetables, artificial light efficiency, in addition to the to the HVAC systems and operating schedules, the building was simulated in software (eQuest) to HVAC systems and operating schedules, the building was simulated in software (eQuest) to analyze analyze the annual energy consumption of the case study to accurately understand the energy the annual energy consumption of the case study to accurately understand the energy consumption consumption capacities on an annual basis. The energy breakdown was as follows, and as seen in capacities on an annual basis. The energy breakdown was as follows, and as seen in Figure 10. Figure 10.

•

•

•

Greater than 30% of 30% the annual consumed energy energy is for cooling during during the summer due to due to  Greater than of the annual consumed is for cooling the summer insufficient windows insulation and low thermal heat loss materials that are used for insufficient windows insulation and low thermal heat loss materials that are usedwalls, for walls, as as mentioned above in Figure 9. Ventilation has no effect on cooling load during summer. mentioned above in Figure 9. Ventilation has no effect on cooling load during summer. Eighteen percent of the annual energy is consumed lighting due the lack of exterior shading  Eighteen percent of the annual energy is for consumed for to lighting due to the lack of exterior devicesshading (during devices the day(during blinds are being used to prevent over glare, so artificial light is being light is the day blinds are being used to prevent over glare, so artificial turned on) in addition to in theaddition insufficient usage of artificial lighting in corridors during the dayduring as being turned on) to the insufficient usage of artificial lighting in corridors the seen in day Figure 5. as seen in Figure 5. Only of the for heating during the winter.  8%Only 8%annual of the energy annual usage energyisusage is for heating during the winter.

Figure 10. Annual percentage. Figure 10. electric Annual consumption electric consumption percentage.

The electric consumption per was month wasasfound as follows, and as in shown in11: Figure 11: The electric consumption per month found follows, and as shown Figure

• • •

 annual High energy annual consumption energy consumption (1160 MWh/year). High (1160 MWh/year).  Energy consumed during the summer (July–September) is greater than the energy consumption Energy consumed during the summer (July–September) is greater than the energy consumption during the winter (November–February). during the winter (November–February).  Maximum energy consumption is about 140 MWh in August. Maximum energy consumption is about 140 MWh in August.

Sustainability 2017, 9, 399 Sustainability 2017, 9, 399

11 of 15 11 of 15

Figure consumption. Figure11. 11.Monthly Monthly electric consumption.

Optimization Resultsand andDiscussions Discussions 3.3.3.3. Optimization Results After addressingthe theproblems problemsthat that affect affect the the building building energy onon thethe After addressing energyperformance, performance,and andbased based passive design optimization in literature, the literature, an interview was organized with architects three architects passive design optimization in the an interview was organized with three working working in the Faculty of Architecture as academic staff and specialists in the fields of building in the Faculty of Architecture as academic staff and specialists in the fields of building energy energy efficiency, green buildings, and renewable energy technologies. The interview was efficiency, green buildings, and renewable energy technologies. The interview was conducted to conducted to explore the energy saving potential and suitable passive design strategies that can be explore the energy saving potential and suitable passive design strategies that can be optimized optimized to ease achievement of net-zero energy goals. The main recommendations for to ease achievement of net-zero energy goals. The main recommendations for optimization can be optimization can be summarized as follows: summarized as follows:  In order to reduce building energy demanded for cooling/heating, maximizing the embodied • In energy order to reduce building energy demanded for cooling/heating, theand embodied preservation by integrating additional insulation materials tomaximizing the walls, roof, floor slabs preservation is needed. Since changeadditional materials (PCM) have materials shown high storage is energy byphase integrating insulation tothermal the walls, roof,[35], anditfloor a recommended solution be integrated into(PCM) the building envelope. slabs is needed. Since phasetochange materials have shown high thermal storage [35], it is a  recommended Provide highsolution openingstoatbe the skylight in thethe building atrium to activate stack effect ventilation integrated into building envelope. in order to decrease overheating in the building and reduce cooling demand during the in • Provide high openings at the skylight in the building atrium to the activate stack effect ventilation summer. order to decrease overheating in the building and reduce the cooling demand during the summer.  Use automated exterior shading devices to avoid overheating and glare in the interior spaces • Use automated exterior shading devices to avoid overheating and glare in the interior spaces and and save lighting energy. save lighting energy.  Use light sensors to reduce unnecessary lighting consumption during unoccupied times. •  Use light sensors to reduce unnecessary lighting consumption during unoccupied times. Increase the U-value of the windows by replacing them with double or triple low-E glass. • Increase the U-value of the windows by replacing them with double or triple low-E glass. With taking into consideration the interview recommendations, alternative energy simulations were conducted in software (eQuest) order to acquire a comparisonalternative analysis of energy energy reduction. With taking into consideration theininterview recommendations, simulations Throughout the energy optimization process, air conditioning system (HVAC) operating timetables were conducted in software (eQuest) in order to acquire a comparison analysis of energy reduction. were takenthe intoenergy consideration. The interior lighting demand and lighting power density (LPD) have Throughout optimization process, air conditioning system (HVAC) operating timetables been optimized according to the daylight measurements and building operating schedules, and all were taken into consideration. The interior lighting demand and lighting power density (LPD) have possible passive design optimization strategies have been applied to the building, such as adding been optimized according to the daylight measurements and building operating schedules, and all high thermal insulation material for walls, as well as increasing the window insulation by using possible passive design optimization strategies have been applied to the building, such as adding triple low-E coating glazing with argon fill as supernumerary glazing for windows, see supporting high thermal insulation material for walls, as well as increasing the window insulation by using drawings in supplementary 1. By conducting a comparison between the baseline run (existing triple low-E coating glazing with argon fill as supernumerary glazing for windows, see supporting energy consumption) and alternative runs after optimizations the results show significant savings in drawings in supplementary 1. By conducting a comparison between the baseline run (existing energy energy consumption after each optimization item, as shown in Figure 12, with a 29% reduction in consumption) alternative runs from after 1160 optimizations results show significant savings in energy total annual and energy consumption MWh/yearthe to just 825.4 MWh/year as shown in run 5 in consumption after each optimization item, as shown in Figure 12, with a 29% reduction in total

Sustainability 2017, 9, 399 Sustainability 2017, 9, 399

12 15 12 of of 15

Table 6, due to the implementation of all optimizations together. This optimization causes a

annual significant energy consumption from 1160 MWh/year just reduction 825.4 MWh/year as shown in run 5and in decrease in cooling/heating loads withto a 38% in total annual consumption Table 6, reaching due to the implementation of all optimizations together. This optimization causes a significant 719.5 MWh/year, as shown as run 6 in Table 6. The optimization can be summarized as decreasefollows: in cooling/heating loads with a 38% reduction in total annual consumption and reaching 719.5 MWh/year, as shown as run 6 in Table 6. The optimization can be summarized as follows: 

• • • • •

Run 2: Window optimization by using triple low-E coating glazing, with argon fill as supernumerary glazing, timber frames 1.0 W/m2with K). argon fill as supernumerary Run 2: Window optimization byand using triple low-E(U-value coating glazing, 2  Run 3: Use of 0.60 m vertical and horizontal fixed exterior shading devices which are 1 m apart glazing, and timber frames (U-value 1.0 W/m K). from each other. Run 3: Use of 0.60 m vertical and horizontal fixed exterior shading devices which are 1 m apart  Run 4: LPD being optimized according to Figure 7, daylight analysis for different spaces, in from each other. addition to the building operating schedules. Run LPD5: being according tothe Figure 7, walls daylight for different spaces, 2K;  4: Run addingoptimized an insulation material to exterior (the analysis existing U-value = 2.62 W/m in addition the building afterto insulation = 0.24operating W/m2K). schedules. 2 K; Run an insulation material the exterior walls (thetoexisting = 2.62 W/m  5: adding Run 6: Heat sensor added to thetoexisting HVAC system operateU-value according to the indoor temperature after the 2above after insulation = 0.24 W/m K). optimization runs (2–5). The temperature is set for 23 °C (winter) 18 sensor °C (summer). Run 6: and Heat added to the existing HVAC system to operate according to the indoor

◦ C (winter) and temperature after the between above optimization The temperature is set for 23 By comparing the differentruns runs,(2–5). it is evident that an improvement in building energy ◦ 18 performance C (summer).could be achieved after optimizing the passive design of the building.

Figure 12. Results of monthly energy consumption simulations. __ Run 1: Baseline energy consumption Figure 12. Results of monthly energy consumption simulations. __ Run 1: Baseline energy (existing consumption). __ Simulation run 2: 7% saving after windows optimization. __ Simulation consumption (existing consumption). __ Simulation run 2: 7% saving after windows optimization. __ run 3: 5% saving after adding exterior shading devices. __ Simulation run 4: 11% saving after Simulation run 3: 5% saving after adding exterior shading devices. __ Simulation run 4: 11% saving optimizing artificial light. __ Simulation run 5: 6% saving after optimizing insulation. __ Simulation after optimizing artificial light. __ Simulation run 5: 6% saving after optimizing insulation. __ run 6: 9% saving after the HVAC energy loads decreases. Simulation run 6: 9% saving after the HVAC energy loads decreases.

Run 1 Run 184.2 84.2 83.783.7 Run 2 Run 260.6 60.6 62.462.4 Run 3 Run 359.4 59.4 61.361.3 Run 4 53.0 54.8 Run 4 53.0 54.8 Run 5 41.6 43.6 Run 5 Run 641.6 36.3 43.6 38 Run 6 36.3 38

85.4 85.4 79.4 68.6 68.6 75.9 65.2 65.2 70.5 55.0 55.0 58.1 51.5 51.5 44.9 58.7 44.9 51.2

79.487.7 75.989.1 70.5 83.2 58.1 71.3 58.7 51.269.7

60.8

87.7 136.8 113.1 113.1 114.5114.5 125.6125.6136.8 89.1 141.4 115.9 115.9 117.9117.9 129.5129.5141.4 83.2 134.0 109.7 110.9110.9 122.7122.7134.0 109.7 71.3 97.8 110.2 120.8 97.2 97.8 110.2 120.8 97.2 69.7 91.6 100.1 109.7 89.9 60.891.6 79.9100.187.3109.7 95.7 89.978.4

79.9

87.3

95.7

78.4

86.186.1 85.785.7 80.680.6 68.8 68.8 67.1 67.158.5 58.5

76.976.9 70.070.0 65.465.4 54.1 54.1 55.2 55.248.1 48.1

TOTAL

TOTAL

December

December

November

November

October

October

September

August.

September

July

August.

June

July

May

June

May

April

April

March

March

February

January

February

January

Simulation

Simulation

Table 6. Different energy consumption results perper month. Table 6. Different energy consumption results month.

1159.8 86.586.5 1159.8 1081.3 64.464.4 1081.3 1024.7 61.961.9 1024.7 53.0 894.1 53.0 894.1 46.8 825.4 46.840.8 825.4 719.5 40.8 719.5

No renewable energy systems are integrated in the building envelope, which play a key role in net-zero energy after optimizing energy efficiency of the building. to the By achieving comparing between the different runs, itthe is evident that an improvement in According building energy annualcould sun path simulation, as shown in Figure the best location to integrate renewable energy is performance be achieved after optimizing the 13, passive design of the building. roof, andenergy the southwest and southeast facades. Nothe renewable systems are integrated in the building envelope, which play a key role in achieving net-zero energy after optimizing the energy efficiency of the building. According to the annual sun path simulation, as shown in Figure 13, the best location to integrate renewable energy is the roof, and the southwest and southeast facades.

Sustainability 2017, 9, 399 Sustainability 2017, 9, 399

13 of 15 13 of 15

Figure13.13. Annual path-red shows thepath suninpath in winter, blue the in sun path in Figure Annual sunsun path-red colorcolor shows the sun winter, blue show theshow sun path summer. summer.

In terms of generated energy, the statistical analysis based on the insolation energy and the In terms of generated energy, the statistical analysis based on the insolation energy and the nominal efficiency of the devices, the results show that 170 photo-voltaic panels covering 340 m2 2are nominal efficiency of the devices, the results show that 170 photo-voltaic panels covering 340 m are needed to provide for the building’s annual energy demands (719.5 MWh), according the previous needed to provide for the building’s annual energy demands (719.5 MWh), according the previous results (Table 6) (1500 m2 2is available on the rooftop of the building). This type of renewable energy results (Table 6) (1500 m is available on the rooftop of the building). This type of renewable energy technology was chosen according to its cost feasibility and accessibility in Cyprus [1,16]. technology was chosen according to its cost feasibility and accessibility in Cyprus [1,16]. 4. Conclusions 4. Conclusions This research investigated how to achieve net-zero energy in existing buildings. And the objective This research investigated how to achieve net-zero energy in existing buildings. And the was how public buildings in North Cyprus can reach net-zero energy goals and play a role in achieving objective was how public buildings in North Cyprus can reach net-zero energy goals and play a role EPBD stated goals for 2020, by taking a public three-story building as a research target, the results show in achieving EPBD stated goals for 2020, by taking a public three-story building as a research target, an almost 30% reduction in annual energy consumption after considering passive design strategies to the results show an almost 30% reduction in annual energy consumption after considering passive reduce the annual consumption and increase the building energy performance. Most of the energy design strategies to reduce the annual consumption and increase the building energy performance. savings were obtained just through optimizing the existing situation, without replacing or increasing Most of the energy savings were obtained just through optimizing the existing situation, without efficiencies. Approximately 11% in energy saving was just from optimizing the existing lighting, and replacing or increasing efficiencies. Approximately 11% in energy saving was just from optimizing 9% just from optimizing the HVAC system. Furthermore, the objective was to develop a strategy to the existing lighting, and 9% just from optimizing the HVAC system. Furthermore, the objective was achieve net-zero energy in the building. to develop a strategy to achieve net-zero energy in the building. After multiple energy modeling simulations for energy saving options, the annual demanded After multiple energy modeling simulations for energy saving options, the annual demanded energy after reduction can be balanced by integrating photovoltaics panels on just 23% of the roof of energy after reduction can be balanced by integrating photovoltaics panels on just 23% of the roof of the building, and the rest available area can be used for generating extra energy to be sell to the national the building, and the rest available area can be used for generating extra energy to be sell to the grid. These results demonstrate that this building, like many similar public buildings in North Cyprus, national grid. These results demonstrate that this building, like many similar public buildings in has a high potential for achieving net-zero energy or even producing energy to the national grid. North Cyprus, has a high potential for achieving net-zero energy or even producing energy to the Furthermore, the following recommendations should be studied for more energy saving potential: national grid. Furthermore, the following recommendations should be studied for more energy potential: •saving Integration of automated shading devices to building windows;

• •  •  •

 

Daylight sensors must be integrated to the lighting system for sufficient energy usage; Integration of automated shading devices to building windows; Upgrading the existing and HVAC insystem terms of efficiency more annual Daylight sensors mustlighting be integrated to thesystem lighting forenergy sufficient energyfor usage; energy savings; Upgrading the existing lighting and HVAC system in terms of energy efficiency for more The feasibility integrating renewable energy sources to the building envelope as additional annual energyofsavings; insulation materials, in terms ofrenewable technical and aesthetics The feasibility of integrating energy sourcesperspectives; to the building envelope as additional insulation materials, in and terms technical and aesthetics perspectives; The economic feasibility lifeofcycle cost analysis of optimizing the existing building towards a net-zero energy feasibility concept; and The economic and life cycle cost analysis of optimizing the existing building towards a net-zero energy concept; and Integrate photovoltaics to the building envelope as an additional insulation material, and as exterior shading devices for windows, which can reduce the cost of insulation and shading and provide energy to the building.

Sustainability 2017, 9, 399

•

14 of 15

Integrate photovoltaics to the building envelope as an additional insulation material, and as exterior shading devices for windows, which can reduce the cost of insulation and shading and provide energy to the building.

Cyprus, as one of the largest islands in the Mediterranean Sea, has a large sector of existing building consuming a great portion of electricity, and has to invest in renovating buildings toward energy efficiency due to the lack of fossil fuel reserves and the high price of imported energy, in addition to take the advantages of energy modeling and simulations softwires which can save time and money in retrofitting buildings towards net zero energy concept. Supplementary Materials: Supplementary materials are available online www.mdpi.com/2071-1050/9/3/399/s1. Author Contributions: Mohammad Abugrain and Halil Z. Alibaba conceived and designed the concept and outline for the paper; Mohammad Abugrain performed the experiments and wrote the paper; Halil Z. Alibaba supervised, provided sources, comments, and major edits for the paper. Conflicts of Interest: The authors declare no conflict of interest.

References 1. 2. 3. 4. 5. 6.

7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18.

Ilkan, M.; Erdil, E.; Egelioglu, F. Renewable energy resources as an alternative to modify the load curve in Northern Cyprus. Energy 2005, 30, 555–572. [CrossRef] Kolokotsa, D.; Rovas, D.; Kosmatopoulos, E.; Kalaitzakis, K. A roadmap towards intelligent net zero- and positive-energy buildings. Sol. Energy 2011, 85, 3067–3084. [CrossRef] Zimmermann, M. Annex 50 Prefabricated Systems for Low Energy Renovation of Residential Buildings; AECOM Ltd.: Birmingham, UK, 2012. Barlow, S.; Fiala, D. Occupant comfort in UK offices—How adaptive comfort theories might influence future low energy office refurbishment strategies. Energy Build. 2007, 39, 837–846. [CrossRef] Roberts, S. Altering existing buildings in the UK. Energy Policy 2008, 36, 4482–4486. [CrossRef] Green, D. Zero Energy Home–Zero Energy Building. 2012. Renewable Green Energy Power. Available online: http://www.renewablegreenenergypower.com/zero-energy-home-zero-energy-building/ (accessed on 8 May 2016). Torcellini, P.; Pless, S.; Deru, M.; Crawley, D. Zero Energy Buildings:A Critical Look at the Definition; National Renewable Energy Laboratory and Department of Energy U.S: California, CA, USA, 2006; p. 4. Marszala, A.J.; Heiselberg, P.; Bourrelle, J.S.; Musall, E. Zero Energy Building—A review of definitions and calculation methodologies. Energy Build. 2011, 43, 971–979. [CrossRef] Recast, E.P.B.D. Directive 2010/31/EU of the European Parliament and of the Council of 19 May 2010 on the energy performance of buildings (recast). Off. J. Eur. Union 2010, 18, 124–126. Buildings Performance Institute Europe. A Guide to Developing Strategies for Building Energy Renovation; Buildings Performance Institute Europe (BPIE): Bruxelles, Belgium, 2013. Uihlein, A.; Eder, P. Policy options towards an energy efficient residential building stock in the EU-27. Energy Build. 2010, 42, 791–798. [CrossRef] Biesbroeck, K.; Klein, R.; Versele, A.; Breesch, H. Design processes for Net-Zero Energy Buildings. In Proceedings of the SB 10 Conference, Maastricht, The Netherlands, 11–13 October 2010. Carmichael, C.; Managan, K. Reinventing Existing Buildings:Eight Steps to Net Zero Energy; Institute for Building Efficiency an Initiative of Johnson Controls: Milwaukee, WI, USA, 2013. Cyprus Turkish Electricity Board. 2002 Annual Report; Turkish Electricity Board: Nicosia, Cyprus, 2002. (In Turkish) AlAjmi, A.; Abouziyan, H.; Ghoneim, A. Achieving annual and monthly net-zero energy of existing building in hot climate. Appl. Energy 2016, 165, 511–521. [CrossRef] Causone, F.; Carlucci, S.; Pagliano, L.; Pietrobon, M. A zero energy concept building for the Mediterranean climate. Energy Procedia 2014, 62, 280–288. [CrossRef] Garde, F.; Lenoir, A.; Scognamiglio, A.; Aelenei, D.; Waldren, D.; Rostvik, H.N. Design of Net Zero Energy Buildings: Feedback from international projects. Energy Procedia 2014, 61, 995–998. [CrossRef] Tzempelikos, A.; Athienitis, A.K. The impact of shading design and control on building cooling and lighting demand. Sol. Energy 2007, 81, 369–382. [CrossRef]

Sustainability 2017, 9, 399

19. 20. 21. 22. 23. 24. 25. 26.

27. 28. 29. 30. 31. 32. 33. 34. 35.

15 of 15

Çomaklı, K.; Yüksel, B. Optimum insulation thickness of external walls for energy saving. Appl. Therm. Eng. 2003, 23, 473–479. [CrossRef] Al-Turki, A.; Zaki, G.M. Cooling load response for building walls comprising heat storing and thermal insulating layers. Energy Convers. Manag. 1991, 32, 235–247. [CrossRef] Gonçalves, H.; Cabrito, P. A passive solar Office Building in Portugal. In Proceedings of the 23rd Conference on Passive and Low Energy Architecture, Geneva, Switzerland, 6–8 September 2006. Gonçalves, H. Solar XXI: Em Direcção à Energia Zero: Towards Zero Energy; LNEG-Laboratório Nacional de Energia e Geologia: Lispona, Portugal, 2010. Alibaba, H.Z.; Ozdeniz, B. Energy Performance and Thermal Comfort of Double-Skin and Single-Skin Facades in Warm-Climate Offices. J. Asian Archit. Build. Eng. 2016, 15, 635–642. [CrossRef] Poirazis, H.; Blomsterberg, A.; Wall, M. Energy simulations for glazed office buildings in Sweden. Energy Build. 2008, 40, 1161–1170. [CrossRef] Alibaba, H. Determination of Optimum Window to External Wall Ratio for Offices in a Hot and Humid Climate. Sustainability 2016, 8, 187. [CrossRef] Susorova, I.; Tabibzadeh, M.; Rahman, A.; Clack, H.L.; Elnimeiri, M. The effect of geometry factors on fenestration energy performance and energy savings in office buildings. Energy Build. 2013, 57, 6–13. [CrossRef] Motuziene, V.; Juodis, E.S. Simulation based complex energy assessment of office building fenestration. J. Civ. Eng. Manag. 2011, 16, 345–351. [CrossRef] Johnson, R.; Sullivan, R.; Selkowitz, S.; Nozaki, S.; Conner, C.; Arasteh, D. Glazing energy performance and design optimization with daylighting. Energy Build. 1984, 6, 305–317. [CrossRef] Grynning, S.; Gustavsen, A.; Time, B.; Jelle, B.P. Windows in the buildings of tomorrow: Energy losers or energy gainers? Energy Build. 2013, 16, 185–192. [CrossRef] Voss, K.; Musall, E.; Lichtmes, M. From low-energy to Net Zero-Energy Buildings: Status and perspectives. J. Green Build. 2011, 6, 46–57. [CrossRef] Autodesk. Autodesk Ecotect Analysis. Available online: http://www.autodesk.fr/adsk/servlet/pc/index? siteID=1157326&id=15362643 (accessed on 25 October 2015). James, J. Hirsch & Associates. DOE2 Based Energy Use and Cost Analysis Software. Available online: http://www.doe2.com/equest/ (accessed on 10 December 2016). Climatemps.com. Available online: http://www.famagusta.climatemps.com/ (accessed on 24 April 2016). ClimaTemps.com. Famagusta Climate & Temperature. Available online: http://www.famagusta.climatemps. com/ (accessed on 15 December 2016). Sharma, S.D.; Kitano, H.; Sagara, K. Phase Change Materials for Low Temperature Solar Thermal. Res. Rep. Fac. Eng. Mie Univ. 2004, 9, 31–64. © 2017 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).