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Energy and Buildings 89 (2015) 183–195

Contents lists available at ScienceDirect

Energy and Buildings

j ourna l ho me page: www.elsev ier .com/ locate /enbui ld

eview

olar considerations in high-rise buildings

ooya Lotfabadi ∗

astern Mediterranean University, TRNC, Turkey

r t i c l e i n f o

rticle history:eceived 1 October 2014eceived in revised form5 November 2014ccepted 26 December 2014vailable online 7 January 2015

eywords:igh-rise buildings

a b s t r a c t

One of the fundamental challenges in today’s world is substituting fossil fuels with renewable energies.All the frequent practices have been intensified in order to utilize the earth and its environment as asource of energy. Hence, architects and planners have a special responsibility toward energy efficiencydevelopment. Here, the overall objective striven for is to introduce solar energy as a permanent renewablesource in order to reduce energy consumption and building initial investment. Thus, the variable outputof utilizing active and passive solar systems and their impact on the decrease of energy usage and totalenergy demands for cooling and heating buildings should be considered as the main objective of thisresearch and the result could be a new definition of architecture and construction, so, this branch of

enewable energy sourcesassive solar strategiesctive solar technology

industry can supply the necessary contributions for sustainable and viable development. Thereby, thisstudy is mainly based on a theoretical approach supported by the outcomes of literature review and casestudy analysis from the solar design aspects. Finally, as skyscrapers are indispensable in modern citiesand as they consume a great deal of energy, considering new ways of benefiting renewable energies canhave a vital role in reducing building energy consumption.

© 2015 Elsevier B.V. All rights reserved.

ontents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1831.1. Research methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184

2. Current energy situations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1842.1. World energy concerns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1842.2. Total global energy demand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1852.3. Energy use in buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1852.4. Renewable energies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1862.5. Solar energy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186

3. Case study analyses: the Pinnacle Tower in London, United Kingdom. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1873.1. Passive solar design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187

3.1.1. Direct solar gain. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1873.1.2. Indirect solar gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1883.1.3. Isolated solar gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1903.1.4. Thermal storage mass. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1913.1.5. Passive cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192

3.2. Active solar design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1924. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194

∗ Correspondence to: No. 72, Haftetir 3, Vakilabad Blvd., Mashhad, Iran.el.: +90 533 871 8887/+98 915 309 3425.

E-mail address: pooya.lotfabadi@gmail.com

ttp://dx.doi.org/10.1016/j.enbuild.2014.12.044378-7788/© 2015 Elsevier B.V. All rights reserved.

1. Introduction

In a country’s development, one significant role is played by

energy. As fossil fuels encompass a very large portion of today’sworld energy consumption, renewable energies that could substi-tute fossil fuels have been sought [1]. Renewable energies result

184 P. Lotfabadi / Energy and Build

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times, while primary energy demand is anticipated to intensify by

Fig. 1. World Primary Energy Supply [6]. RES: renewable energy sources.

rom two distinct issues. Concerns about preserving energy sup-lies against unexpected crisis and the issue that fossil fuels willome to an end have led to the renewability [2]. Mal-adaptation,he exploitation of the earth’s energy sources, which has led to sus-ainability, may cause next generations to have a poor life in future.uring the past three or four decades, a lot of attention has beenaid to these two important matters and obviously to the influencef international relations and the political decisions in all levels3].

However, although in many countries around the world, renew-ble energies are considered as a very important supply, lesshan 10% of primary energy supplies are renewable energies [4]Fig. 1). If the whole globe is considered, the initial energy sup-lies are renewable energy sources. In developing countries theost significant ones are hydro energy and fuels are based onood, solar and wind energy seems to consist a small portion

5].Using renewable energy sources surely reduce environmen-

al damages and lead to sustainability. The rate of these kinds ofnergy consumption is nearly 8%. Those renewable sources help toecrease the global warming or to create a sustainable waste [7].evertheless, each kind of renewable energy sources imposes someind of damage to the environment. However, in comparison to theurrent conventional systems, the use of this new source of energys much cleaner and sustainable [1,8,9].

It is conveyed, that many of today’s technologies are still in theeveloping phase and other fields require further research, how-ver, the current era, compels humans to develop new ideas andeek for innovative concepts. Therefore, the idea of developing andesigning future buildings is actively supported by a number ofrchitects, engineers, and civil engineers [10]. There are so manyenewable energy alternatives, but under the study limitation andcope, just solar energy, which seems to be more practical in high-ise buildings, will be analyzed.

Correspondingly, in today’s world, the rate of energy usages growing rapidly in accordance with the industrial develop-

ent, and the population growth is becoming greater. Thereby,s few studies have been done by architects such as Ken Yeangn the amount of energy consumed in high-rise buildings, theuthor attempts to make viewpoints of some architects, construc-ion builders and also users more clear about the influences ofsing passive solar strategies and active solar technologies onall buildings. Therefore, by considering the use of solar passivetrategies and active technologies as an alternative in high-riseuildings, this study tries to fill some of the current gaps as much

s possible and its proposed fundamental message is changingrchitects’ and construction builders’ view in dealing with the sub-ect.

ings 89 (2015) 183–195

1.1. Research methodology

This research is mainly based on a theoretical approach, whichis supported by the outcomes of a literature review and case studyanalysis. Therefore, the descriptive research method is used in thisstudy. This method is used in order to gather information aboutthe existing type and the amount of energy consumption in thebuilding sector. So, at the first phase, it is a type of study, which isessentially concentrated on describing the degree and the conditionof the current renewable energy usage situation in detail.

On the other hand, it involves fieldwork and more especiallysystematic review as a combination of two main phases, qualita-tive and quantitative methods of data collection. As the first step,the research is performed to become aware about the effective-ness of using passive solar strategies and active solar technologiesthat architects would like to apply in the skyscraper design. Then,the study aims to prioritize and compare the effectiveness of theseissues by analyzing the case study and summaries the resultsin Table 4. Therefore, for data evaluation and computation the‘Autodesk Green Building Studio’ and also ‘EnergyPlus’ softwareare used.

The simulation tools can generate the design alternative thatexplores the energy performance of the range of options. With rela-tive minimum options you can get simulations results that taking toaccount of the proposed building climate and building type, enve-lope properties and active systems. Because the simulation takingto the account the interdependency of the building as a whole sys-tem, energy simulation results are useful to keep score as the workto reduce the building energy use.

‘Autodesk Green Building Studio’ automatically reads all build-ing geometry data produced by a gbXML-enabled BIM or 3D-CADprograms, such as ‘Autodesk Vasari’ and ‘Autodesk Revit’, whichare used in this research, to perform a thermal simulation anal-ysis (Chart 1). In this case, minimum manual inputs, which arerequired, are ‘zip code’ and ‘building type’. Users may specify addi-tional input parameters to the extent they have been enabled inthe BIM/CAD program’s GUI. All other simulation variables sup-plied by the software may be viewed and edited in other DOE-2.2or gbXML compatible applications in order to calculate buildinghourly energy usage, which has been used and trusted in industryfor many years.

2. Current energy situations

2.1. World energy concerns

In today’s world, energy sources have performed necessaryfunctions, such as creating heat, supplying drinking water, gener-ating power for certain appliances, electrical products and so on[5]. With efficiency in mind, it is worthwhile for us to create toolsthat can produce usable energy without excessive consumption.This means striving to equalize the power input and output of agiven system, so that, the running of the system consumes no morethan is absolutely needed to perform the intended function withminimal or no residual waste [11].

Accordingly, in recent years, energy demand is growing. It iscertainly because of the annual population growth rate, which isnow about 2% and is also more in some countries. This quantity isexpected to double by 2050, and improving standards of living bycontinuing economic development, must be considered as a result.Also, by 2050, global energy services demand will increase up to 10

1.5–3 times [5,12].Thus, more environmental considerations should be taken

from the public and industry section, both in developed and

P. Lotfabadi / Energy and Buildings 89 (2015) 183–195 185

Table 1The EnergyPlus software input data samples for the Pinnacle Tower.

Quantity Note Description

Latitude 51◦50′72′′ N The geographical (North/South) coordinates of the test buildingLongitude 0◦12′75′′ E The geographical (East/West) coordinates of the test buildingSurface Azimuth 240◦ Direction surface faces (East: +90◦; West: 270◦ or −90◦)Surface elevation 0◦ Elevation of surface (Vertical: 0◦; Horizontal: 90◦)Day number 92 (Summer) 1, 2, 3, . . ., 365Solar time Computed Function of time and longitude, day number and time zoneSolar hour angle Computed Function of solar time

Source: Author (2014).

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It seems to be necessary to be aware of this fact, that the build-ing and construction sector globally use 30–40% of the total primaryenergy [31]. It is believed that the building sector can potentially

Chart 1. Autodesk Green Building

eveloping countries. It is believed that in future people willecome aware about pollution problems and take responsibilities,

n order to account the environmental costs; some energy source’srice has multiplied. Consequently, estimations show that both pri-ary energy demands and global energy service needs are growing.t the same time, people will be more concerned about climatehange in future and its causes such as acid rains, stratosphericzone depletion and so on [14].

Climate change, which specifies different parts of the world,efers to a change in weather patterns not in a short time [15].xperts believe that the world is going warmer (global warming).his trend cannot just be explained by natural climate variability.uman activities, especially, burning oil and coal have made thelanet warmer [16,17]. This has occurred because of heat beingrapped in the atmosphere, so the more greenhouse gases are pro-uced, the warmer the planet will be [18,19].

The core of the problem in terms of carbon dioxide emission peread lays in the developing and industrial countries inequalities.enerally, CO2 emissions from developed countries are displaying

ess sign of decreasing [20,21]. In this case, the US average emissions 23% of the world’s total now, which is twice the European averagend is still increasing. The average citizen in the North Americanontinent, which includes US, Canada, Mexico and so on, annuallydds nearly 6 tons of carbon to the atmosphere per year. This isbout 2.8 tons per person in Europe, where the case study is selectedrom [22].

.2. Total global energy demand

Today 80% of the world’s energy use is based on fossil fuels.uring the past centuries less fuel was consumed and this portion

elated to the present century. The amount of oil consumption hasncreased since 1990 together with natural gas consumption. So,t the end, the total amount has increased. It is clear that theseatural resources will end up one day (Fig. 2). The allocation ofolar energy increased and the rate of renewable energies remainedtatic. In 1990, the portion of biomass and waste was about 11%nd it is still the same today. If we deduct the traditional biomassrom the total amount of renewable energy forms such as wind,

olar energy, hidden energy in tides and geothermal energy, weet 0.45% of world primary energy use in the same year. This shares 0.55% for 2006. Although the contribution of renewable energiesas doubled since 1990, still it is a very poor performance [23].

data input and analyzing method.

Based on the present data (2008) total energy consumed peryear is more than 131,138 PWh1 or 473,500 EJ.2 The oil’s share is35%, natural gas’s is 20.7%, nuclear sector generates 6.3%, hydroenergies consists 2.2%, waste and biomass produce 10%, coal hasa share of 25.3% and other sources generate 0.5% (Fig. 3) [25]. Inrecent years, mankind has welcomed the use of renewable energysources due to the fuel crisis caused by its price increase and globalwarming [26].

According to the ‘International Energy Agency’ (IEA) the oilresources will end up in about 2040; meaning that the oil con-sumption will increase up to 40% between 2006 and 2030 [13]. Theworld has used about 800 billion barrels of conventional oil so farand the cumulative total is approximately 900 billion barrels. Theresource base of conventional oil is precisely estimated to be 2 tril-lion barrels, so only 300 billion barrels would be left by 2030 andthis amount is enough only for ten years supply [23]. Analyze thisinformation considering this fact that renewable energy sourcesrepresented about 8% of the global energy consumption [27].

2.3. Energy use in buildings

In general, in every construction process level, there are four dif-ferent levels of impacts on the environment. They can be consideredas the impacts of inputs, impacts of outputs, impacts of the systemand finally impacts of the environment itself on the system. To bemore clear, in the construction sector, it can be seen that about 40%of the raw materials by weight are used in this part globally eachyear [28], and also between 36 and 42% of a nation’s energy outputis used in constructions.

Building outputs are something about 20–26% of landfill trashes,and finally 100% of energy, which is consumed in buildings is lostin the environment [29]. Therefore, to have more control on energyusage in buildings, the role of architects is significant toward theimprovement of the environment and also regarding to a moreecological future. This issue – energy – is important for architectsbecause the building section itself represents about 40% of the totalenergy used throughout the entire world [30].

1 PWh: Peta Watt hour.2 EJ: Exa Joule.

186 P. Lotfabadi / Energy and Buildings 89 (2015) 183–195

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Fig. 2. World’s li

ecrease primary energy usage and also decline the CO2 emissiony utilizing more renewable energy sources. Thereby, to develophese potentials, several strategies can be used, especially in theonstruction sector, including energy efficiency requirements inuilding standards [32].

.4. Renewable energies

Nowadays, energy is produced in three different ways through-ut the world: crude fossil fuel such as oil, coal and wood, whichas extensively been used, nuclear power, which is accessible toll countries, however, it is only in control of developed countries33]. Renewable energy is essential for development and is easyo use everywhere in the world. It causes less pollution than fossiluels [34]. It is available and abundant in nature. The demand forhis kind of energy is about 8% of the world energy demand [7].ecent developments in technology and suitable policies together

ith the use of renewable energies such as wind energy, solar radi-

tion, geothermal, biomass, as well as the more traditional sourcesuch as hydro power can lead the renewable sources to having ahare of 50% of the entire energy demand by mid 21st century [35].

Fig. 3. Perception of different energy

uels supply [24].

According to what was explained above, it can be concludedthat nuclear power is associated with some problems such as itswaste disposal and accidental catastrophes caused by different nat-ural and human factors and releasing heat into the atmospherethrough its cooling system, while fossil fuel has a lot of disadvan-tages like damaging the environment [36]. Renewable technologiesexcept biomass do not involve in the burning process, so that atmo-spheric pollutants such as carbon dioxide, nitrous oxides, sulfuroxides, as well as significant waste byproducts such as ash arenot produced. Considering the health problems of these wasteproducts, renewable energy sources are far more better than non-renewable technologies [2]. Renewable energies provide a rangeof wide choice in energy supply markets; they create new localemployment opportunities and enhance the security of supply [34].

2.5. Solar energy

Solar radiations can be considered as the primary source ofrenewable energy. Although it can take part as a direct energysource, it impacts the earth’s climate. Energy opportunities aredeveloped from waves, tides and wind, which are also a host of

usage sources (year 2010) [27].

P. Lotfabadi / Energy and Build

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Therefore, to analyze the effects of the direct solar gain featuressuch as orientation and daylighting the ‘EnergyPlus’ software, byusing data of Table 1, which mostly exist in the EPW file, has begunthe simulation process. Hence, it must be mentioned that in order

Fig. 4. The Pinnacle Tower [39].

iological sources. This kind of energy can specifically be used inuilding sector as an energy source. However, this source of energy

s considered as two parts:

Passive solar energy: For many decades, passive solar energy gainhas been used as environmental factors. Anyway, the more theglobal warming debate has been put forward, the more pressurehas been put into designing buildings, which causes the max-imum use of free solar gains for heating, cooling and lighting[37]. As the energy, released from fossil fuel, can be substitutedwith passive solar energy, it could lead to the reduction of CO2emission.

Furthermore, passive solar design configurations itself can beseparated into five sections as follows [38]:• Direct solar gain• Indirect solar gain• Isolated solar gain• Thermal storage mass• Passive cooling

Active solar energy: This item focuses on obtaining usable heatfrom the solar radiation. For instance, in case of temperate cli-mates the most suitable application of solar radiation is usingsolar radiation to supplement a conventional heating system orto generate power [37].

. Case study analyses: the Pinnacle Tower in London,nited Kingdom

The Pinnacle or the Bishopsgate Tower is one of the latest Keneang’s projects, which totally illustrates the characteristics of hisreen and ecological skyscrapers (Fig. 4). It is a type of skyscraper

ings 89 (2015) 183–195 187

with the original exterior ‘helter skelter’3 design, located at Bish-opsgate street, London. It is a mixed-use complex with emphasison residential use. The project construction had been started inSeptember 2008 by Kohn Pedersen Fox as a head architectural officeand CBRE Group, Inc. With a height of approximately 288 m, it isestimated to be the second tallest tower after the ‘Shard’ in the UKand also in the European Union.

3.1. Passive solar design

3.1.1. Direct solar gainDirect gain concentrates on controlling the amount of direct

solar radiation reaching the living space. This direct solar gain isa critical part of the passive solar house designation as it imparts toa direct gain [40]. Thus, it is a kind of design technique that mainlyconcentrates on the sun-facing facade. Solar radiations are directlyadmitted into the space concerned. The main design attributes areas follows:

• Opening for solar radiation should be placed on the solar side. Theangle is about ±20◦ of south in the Northern Hemisphere [40].

• West side facing windows might increase the risk of summeroverheating.

• It is better to use double or triple glazed windows with low emis-sivity glass (so called low-E).

• In design, the most occupied living spaces should be consideredon the solar side.

• In order to absorb the heat and set thermal inertia that decreasethe temperature fluctuations inside the building, the floor shouldbe constructed from high thermal masses.

The Pinnacle project is totally found on the Yeang’s ecologi-cal design agenda by considering some basic principles, such asbuilding orientation and configuration and also using green spacesand landscaping in its conceptual design. So, it is constructedconsidering the passive low energy response principals. The entireconstruction form is controlled by the site sun path and summerand winter windrose status.

In order to obtain solar protection in summer, lift cores arelocated at the west and northeast facades of the building and inwinter southeast units and central landscaped circulation area havea maximum solar gain. As this building is a semi cubic skyscraperform, rotated approximately 30◦ in a North-East direction in orderto ensure optimum ventilation and daylight penetration from thesouth solar direction in two facade sides (Fig. 5). This is also due tothe fact that the prevailing winds in London come from this direc-tion (Fig. 5). Therefore, it can benefit from most solar radiations andwinds in all directions. Meanwhile, each facade contains vast trans-parent windows that can provide better air ventilation and help toachieve maximum daylighting.

The ‘Autodesk Green Building Studio’ web service software cangenerate geometrically accurate and detailed input files for most ofthe energy simulation programs, automatically. The software usesthe DOE-2.2 simulation engine to compute energy performance andcreates valid input files for ‘EnergyPlus’.

3 A helter skelter is a funfair or amusement park ride with a slide built in a spiralaround a high tower.

188 P. Lotfabadi / Energy and Buildings 89 (2015) 183–195

Fig. 5. Temperature differentiation, Sunpath and Wind Rose for the Pinnacle Tower [39].

Table 2The Pinnacle Tower site and weather summary – TMY2 format.

Weather type Lapse rate Latitude Longitude (local site) Sea level altitude Site altitude Ground reflectivity Site

Temperate 8.3 ◦C/km 51◦50′72′′ N 0◦12′75′′ E 24 m 32.6 m ∼0.17 m/ns Flat, unobstructed

Dew point temperature(constant)

Temperature Humidity ratio Mean annualwind speed

Maximum annualwind speed

Global horizontalsolar radiationannual total

Direct normal solarradiation annualtotal

Diffuse horizontal solarradiation annual total

m/s

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12 ◦C 17.5 ◦C 72 gr/lb 3.5 m/s 7

ource: Drawn by Author (2014).

o benefit ‘EnergyPlus’ software the input data must be in TMY orMY2 format, which are available in the EPW files.4

The Typical Meteorological Year format data (TMY) are threeonth long data files that are applied in the original field trials of

he test procedure; the TMY2 format data are year-long data fileshat may be more convenient for users [1] and here are used forase study analysis. However, in this research, the input weatherata, which is used for the software analysis and simulation is aext-based format retrieved from the TMY2 weather format.

Likewise, in order to attain common format output, the ‘Opentudio Results Viewer’ is used. It reads the output of ‘EnergyPlus’nd displays the data in the form of line plots and also two dimen-ional flood plots. Eventually, analyzing TMY2 file and Table 2 datallustrates that by applying some principles such as orientation,dequate amount of green spaces and openings to benefit fromatural daylighting, the Pinnacle Tower total energy consumption,ecreases as much as about 20% of an ordinary high-rise building

n that district.

.1.2. Indirect solar gainIn this case, a heat absorbing element is added along with the

ncident solar radiation and space to be heated. Therefore, the heat

4 EPW files could be downloaded from the web site for EnergyPlushttp://www.energyplus.gov).

∼1050 kWh/m2 ∼750 kWh/m2 ∼135 kWh/m2

transfer is in an indirect form. This is often a wall, which is placedbehind glazing facing toward the sun. This thermal storage wallcontrols the flow of heat into the construction. Thus, the mostimportant factors contributing to the design function are as follows:

• The wall heat flow can be modified by its thickness and materials.For instance, for the residential spaces, this amount is between 20and 30 cm in order to make some delay for this heat transactionand its thickness depends on the occupancy periods.

• In order to prevent heat loss, glazing is used on the outdoor space.It also helps to retain the solar gain by taking advantage of thegreenhouse effect.

• Approximately 15–20% of the floor area, which emits heat, shouldbe dedicated to the thermal storage area.

• To derive more instantaneous heat benefit, air can be circulatedfrom the construction through the air gap among glazing andwall, and back into the room. In this adjusted and modified form,this element is commonly referred as a trombe wall (Fig. 6). Heatreflecting blinds should be inserted between the thermal wall andthe glazing to limit heat build-up in summer [37].

In this case, in designing the facade of the Pinnacle Tower espe-cial attention has been applied. It is designed in a way that allowsmaximum amount of dilution to enter into the building. Theyare also preventing cold winds in winter by benefitting from the

P. Lotfabadi / Energy and Buildings 89 (2015) 183–195 189

Table 3The Pinnacle Tower annual building energy usage [39].

Type Area (m2) Energy (kWh/m2) Annual energy consumption (kWh)

Housing 22,990 200 4,598,000Retail 8660 250 2,165,000

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ultilayered external walls that check both living units and indi-idual garden terraces.

Mesh-screen wind-breaker elements reduce the inflow of stronginds, and adjustable, insulated shutter doors are supported by

oth large double-glazed windows and internal shutter doors thatetain internal heat at night. Finally, the landscaping and plantingf private gardens and communal sky-parks contribute and act as

wind buffer and are a kind of protection against solar radiation inummer to avoid overheating of indoor spaces.

In other words, the building exterior facade pays attention tooth bioclimatic and esthetic aspects of the London city environ-ent (Fig. 7). As mentioned, the elevation of this high-rise building

s multi layered, whose outer layer is a versatile wind shield madef metal mesh. This layer can be opened in order to make ventila-ion better. The second layer is timber folding doors that are eitherhort or angled to protect the terrace from the sun in summer andot to block the view out. To gain better insulation, the next layer isouble glazing. Finally, in order to obtain further insulation prop-rties, each apartment unit is distinguished with adjustable timberanels.

‘Autodesk Green Building Studio’ is a flexible cloud-basedervice that allows users to run building performance simulationso optimize energy efficiency earlier in the design process and cre-

te a ‘Revit’ model very early in the design process. A simple modelllows users to compare forms and gross amounts of glazing, ori-ntation, shading and so on. In this case this software only requiresurfaces, openings, and rooms to simulate the building.

Fig. 6. Passive energy gain by

6,763,000

It incorporates ‘Google Maps’ to facilitate entry of the projectand select the appropriate weather file. This is done by enter-ing the project’s address or postal code in the location text box,and click on the Find Location button. It should be mentionedthat Autodesk Green Building Studio Stations are based on recent“actual year” weather data rather than TMY2 and CZ2 stations,which are based on 30-year averages of weather data. So, thismethod is much easier, faster and accurate than other existingmethods.

‘Autodesk Green Building Studio’ automatically generates thebuilding energy analytical model and forms a normal architec-tural model. Therefore, by using this method it is estimated thatindirect solar gain factors can leads to approximately 35% reduc-tion in building energy demand. However, in case the softwarecannot find your parameter it uses the default values, whichare based on building energy standards, which are appropriatefor the building type, size and location in order to generate themodel.

Accordingly, the building multi-layer facade system in differentseasons works as follows:

• On winter days the sun rays reach the facade nearly horizontally

so in spite of the wind shield being drawn the rays penetrate themesh and blinds.

• For higher energy efficiency in heating section all movable parti-cles are drawn on cold winter nights.

solar-Trombe wall [41].

190 P. Lotfabadi / Energy and Buildings 89 (2015) 183–195

multi

•

•

Fig. 7. The Pinnacle Tower

On breezy summer days, timber folding doors only let the desiredamount of the sun rays enter the room and glass doors and windshields are left open to let the breeze in and make an enjoyable

atmosphere in terraces. The movable floor grating is also removedfor inter-floor and cooling the metal mesh acts as sun shields.In a hot summer night, all layers are opened for maximum naturalcooling and cross ventilation.

Fig. 8. The Pinnacle Tower landscaped r

layered facade system [39].

3.1.3. Isolated solar gainThis means benefiting solar energy in living areas through using

a fluid like water or air by forced or natural convection. Heat can

be gained through solarium, sunspace or solar closet [42]. Gener-ally, this item can be considered as an extension space, which isadded to the living area. It can be used as a solar heat store, a pre-heated for ventilation or also as an adjunct greenhouse for plants. As

amp and circulation system [39].

P. Lotfabadi / Energy and Buildings 89 (2015) 183–195 191

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Fig. 9. The Pinnacle Tow

onservatories are often heated, they are a net contributor to globalarming, sunspace should be completely insulated in order to pre-

ent the building from getting cold in winter and being too hot inummer.

20–30% of the area of the room to which the glazing is attachedhould be covered with it. In ideal conditions the amount of heatbsorbed in summer should be stored to be used in winter andnally there should be controlled spaces between the building andhe conservatory for the air to flow [37]. In order to benefit the localatural energy reserves appropriately, apart from global radiation,he temperature, humidity and wind, specific climate data corre-ponding to the geographical location are the most considerableactors.

This skyscraper design is a common plan-form that has a radialrrangement. In other words, the apartments are creating a ‘fan’rrangement on the northern and southern side of the project.he peripheral accommodation encloses an internal atrium, whichises through the building surrounded by a continuous landscapedamp (Fig. 8). This initial pedestrian circulation system creates therincipal component of the skyscraper, which is fundamentally aadial-spiral shape. The site, which was defined as a closed ecosys-em by Yeang was rehabilitated by the planted facades and terraceshat augmented the atrium landscaping.

Therefore, one of the main characteristics is the weather-rotected landscaped core. The core is playing a significant role

n gaining maximum solar radiation in winter and in mid-seasons.owever, it is used as a type of shading system to protect the build-

ng from the summer sun. Moreover, these lift cores, which areituated on the northeast and west elevations, arrange a solar pro-ective buffer zone for summer. However, in winter, low-angle sunadiations are able to enter the green spaced circulation atrium

lding configuration [39].

(Fig. 9). Also the residential units, which are located on the south-east, gain maximum solar radiations.

Furthermore, one of the main design characteristics of thishigh-rise building is its vegetated terraces and well planted (greendesign) facades. These green spaces are continued to the ramp fromthe ground floor to the upper level of the tower. The entire greenarea of this building is approximately 40.700 m2, which has theratio 1:1 of gross useable area to gross vegetated area. Vegetationand landscaping within the private gardens and sky-parks buildingact as a wind buffer, while giving users a more human environment.In summer, vertical landscaping acts to obstruct, absorb and reflectsa high percentage of solar radiation, thus, reducing ambient tem-peratures. The damp surfaces of grass and soil will also contributeto a cooler and healthier building.

In this level the ‘Autodesk Revit’ model has been analyzed. Thismass model contains the general building geometry, including thenumber of rooms, the connections between rooms and their rela-tionship to the exterior, exposure, and aspect to the sun, like theshape and total area of built surfaces and also openings. By thesetypes of information as an input, the ‘Autodesk Green Studio’ cananalyze the building conceptual mass model. Therefore, in brief,after setting few parameters, such as building location, type, floorsand basic construction and system, and also as this software iscloud-based, it provides the results very quickly. So, analyzing theeffectiveness of isolated solar gain factor in this project determinedthat green spaces can lead to about 40% saving energy in annualbuilding heating and cooling.

3.1.4. Thermal storage massThe solar radiations cannot be benefited all day, so that it has to

be applied for heat storage, or thermal mass to keep the buildings

1 Buildings 89 (2015) 183–195

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92 P. Lotfabadi / Energy and

arm. This is designed for only one or few days, which is possiblehrough indirect solar energy gain, such as; trombe wall, a cistern,ater wall or roof pond, a ventilated concrete floor [43].

However, it must be noted that, in Pinnacle Tower as a casef ecological architecture, while this skyscraper makes so manyositive gestures in order to be environmental friendly, still there

s the possibility of going further. A large amount of light enters theuilding and there is no way to store this free energy to utilize it forhe building and another way to lower energy consumption in skyark was making the floors of stone or tile. However, the weight ofhe above materials must be considered as a significant matter inesigning high-rise buildings.

The ‘Autodesk Green Studio’ simulation tools can generate theesign alternative that explores the energy performance of theange of options. With relative minimum options you can get simu-ations results that take to account of the proposed building climatend building type, envelope properties and active systems. As theimulation takes to the account of the interdependency of the build-ng as a whole system, energy simulation results are useful to keepcore as the work to reduce the building energy use. Thus, analy-is shows that, for instance by using thermal mass materials and/orark surface walls, about 95% of the gained solar energy is converted

nto heat.

.1.5. Passive coolingThe efforts done to minimize energy consumption and improve

ndoor thermal comfort, which mostly focus on heat dissipationnd heat gain control in buildings, are referred to as passive cooling.his is possible in case we prevent heat from entering the interiorheat gain prevention) or remove heat from the building (natu-al cooling). Architectural design of building components togetherith natural environment use natural cooling to dissipate heat [44].owever, in this case an innovative passive cooling system is notpplied.

.2. Active solar design

This type of solar technologies is mainly used in order to producether useful types of energy from solar radiations. This new energyype is a kind of thermal energy to provide power generation, cool-ng, heating and hot water supply. Therefore, in the conversionrocess, one type of mechanical or electrical equipment is used andhis is happening in order to maximize the effect of solar energy inuildings.

To achieve more sustainable design, gallium arsenide photo-oltaic cells combined with a rainwater catchment or a rain-screenn south-east facade are used. PV panels are utilized in order tobtain more energy self-sufficient building and sustainability. Theollowing table illustrates the amount of annual energy usage of theinnacle Tower (Table 3).

Therefore, in this case by covering the entire south east eleva-ion, which includes ramp and PV panels with 30◦ angle (Fig. 10),he total covered area can be calculated as follows:

1 m × 0.5 m × 50 (storeys) = 775 m2

Considering the potential power output, it is estimated that pho-ovoltaic panels’ efficiency is about 13%, which means 100 kWp (kWeak). Potential energy generated from a 100kWp source, in theest situations, with no shading effect of other high-rise buildings,ptimal PV angles and building orientation, it can annually gener-te approximately 70,000 kWh. However, by considering the actual

ituation such as locating PV tiles in the southeast facade, insteadf south, this amount is reduced to about 50,000 kWh. Therefore,ccording to Table 2 these PV panels can provide nearly 0.7% of thentire annual building energy needs (Fig. 10) [39].

Fig. 10. Photovoltaics system [39].

Apart from the above considerations, the most widely used windturbine types are the upwind, three-blade horizontal axis type,whether the rotor spins in front of the tower about a line paral-lel to the horizon. The vertical axis primarily lift type turbines arenot so efficient in energy production and their use can be justified asan architectural element of the integrated design for this building.To obtain sufficient power from a single turbine (50 kW<), typicaldimensions of the main mast and the blades are 30 m and 10–15 mrespectively, making this type of application unsuitable for the site.

However, using smaller turbines about 6–10 kW, with the blade

size of approximately 4.5 m is more appropriate for this building.Furthermore, most applications use tail vanes to point the rotorinto the wind. Finally, it should be mentioned that the effect of usingthese types of generators can lead to producing about 1% of building

P. Lotfabadi

/ Energy

and Buildings

89 (2015)

183–195

193

Table 4The evaluation of the Pinnacle Tower.

Source: Drawn by Author (2014).

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nnual total energy consumption. Also from the economical pointf view the payback period of the turbine, which is used here isbout 23 years.

The following table summarizes the effect of using solar design-oth passive strategies and active technologies- and other sustain-ble technologies in the Pinnacle Tower, which can be comparedith ordinary high-rise buildings that do not benefit from these

ypes of technologies (Table 4).

. Conclusion

Eventually, by considering today’s global warming and world’sconomy, no one doubts that current energy sources are not inter-inable. So, the necessity of sustainable design for the future

s inevitable. Moreover, in theory, this potential is available bynergy efficient design, which can cause the design to changerom being uncertain into a confident science. This kind of energyonservation might be meaningfully reached in high-rise buildingesign.

In order to evaluate high-rise buildings in terms of solar energyse, the author analyzes the case studies from both passive solartrategies and active solar technologies’ aspects. In the first phase;irect solar gain, indirect solar gain, isolated solar gain, thermaltorage mass and passive cooling as a meaningful factor to obtainassive strategies are evaluated. On the other hand, this case isnalyzed from the use of active solar technologies and the resultsre summarized in Table 4.

Therefore, in the Pinnacle Tower, which is considered as a bothctive and passive solar design high-rise building; 30◦ orienta-ion to north-east direction and weather protected landscape core,hich is supported by operable transparent windows considered

s effective factors in order to gain direct solar radiations, leads topproximately 30% energy saving (Table 4). Accordingly, in order tonderstand the effect of indirect solar gain, the different multipleac ade systems are analyzed. In the Pinnacle Tower four fold lay-rs fac ade system has a meaningful effect on the buildings’ energyemands. So, the result illustrates that energy reduction is about5% in this case.

The next factor is isolated solar gain, which due to the researchimitations; the solar chimney effect is analyzed. Thus, in thisection, in the Pinnacle Tower, central atrium is used as a typef natural ventilation chimney, which is supported by operableindows and some kinds of green spaces, which leads to about

0% energy saving. Apart from these considerations, this towerenefited from the prevailing wind direction in the atrium. Unfor-unately, this high-rise building is not benefited from the passiveooling system and the thermal storage mass capacity; however,t has the potential to gain this character by changing their greenpaces floor with some kind of thermal mass storage materials. Ashe material weight is a significant factor in designing high-riseuildings, the more practicable suggestion is to apply these typesf considerations in the facade system design.

Finally, high-rise buildings have great potential to gain solaradiations because of their vast facades. Analyzing case studiesllustrate that applying solar passive strategies in high-rise build-ngs have a meaningful effect on reducing the total annual coolingnd heating energy demand. These strategies can be applied anddapted to high-rise buildings by using direct solar gain, indirectolar gain, isolated solar gain, thermal storage mass and passiveooling systems. On the other hand, considering active solar tech-ologies can also add extra potential by providing part of the

uilding necessary energy demands. Although this amount is notuge amount in the case study, it can be improved by integrating PVanels and other solar active technologies in the high-rise buildingacades.

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