skyscraper rapid transit iSRTj concept

iito informal

SRT stations • «very 3 segment Intervals Total stations ■ 18

In Ihr I tfX, MY, Triwc > this takes Ihr Ir.rm tjf « (.illy automated continuous SRT (Skyvuper Rapid Tranutl system th»t WMvn together the dill» fill programmatic »ones into a looping public /one where secondary streets and public sqiiaies may r»tend oM tlx» puM" realm I his SRT system convsls ol » pai' til monorail twin lr»'S| (/•<"• lor ascension the other fc»r defending! wi «h main a lull turn every three segments u- If* m SRT station-. are plarrd at every thier segments, providing * / < to f "W pavilions and stir-.

SRT stations • «very 3 segment Intervals Total stations ■ 18

, tiro I'/S'

These projects, which are both centred on residential accommodation and mixed-use, and are both the subject of competitions, mark Yeang's entry into the UK scene, with proposals for two major locations in the city. While the development briefs and sites vary in detail, both are essentially configured as a range of peripheral towers with a centralised facility, such as market square or transport interchange and plaza within the site. Both projects are associated with railways tracks, which are in boundary or centralised positions. Logically, as both projects are located in London, either north or south of the River Thames and have similar programmes with the emphasis on residential use. Yeang has applied similar concepts, criteria and methodology to each scheme. These factors of the designs exhibit the characteristics of Yeang's green skyscraper' and vertical urbanism propositions

Yeang's approach is based on three major issues and their incorporated resolution These include Social Sustainability, Environmental Sustainability, and Passive Low Energy Responses, and expanded in detail these form the overall framework and content of the projects. Yeang's controlling concept of the 'City-in-the-Sky', recurring in almost all of his high-rise work, envisages the skyscraper "... seen as a microcosm of the city, containing within itself the inherent elements of a city block ... parks, shops, entertainment centres, community facilities, social housing" ... 1 and other residential accommodation types.

Yeang then outlines the benefits of this intensified vertical urban condition, which includes local employment resulting from mixed use, a balanced mixture of residents depending on income and accommodation requirements, yet with common facilities, such as parks and shopping streets provided on a shared basis. The arrangement then allows for basic amenities such as local stores, postal boxes, chemist and so on, to be provided within the building. Further, and characteristically, Yeang emphasises the creation of a healthy landscaped environment, with "... spatial progressions of public open spaces (parks in the sky) to semi private (entrance courts) to private open spaces (balconies)." 2

In the case of both projects Yeang's agenda for Environmental Sustainability is identical, and is drawn directly from his 'Green Skyscraper' treatise, and his open general systems framework. 3

This includes the interconnected set of external and internal interdependences, together with the external-to-internal exchanges of energy and matter and vice versa, the designed systems output of energy and materials. To this Yeang then adds the considerations of Passive Low Energy Responses both by Building Configuration and Orientation, and by Landscaping and Vegetation. Thus both designs, although varied in detail, are based on Yeang's full agenda for an ecological architecture, in this case related to the temperate climate of London.

From this shared conceptual basis, the two projects can be reviewed indep, jenny, within a closely related typology

I 4. e<shot»«*te Towen v* Elephant wd Cast* Eco-Towen'. Pro»«« *<*« 2000

- l The Green Skytciapei op at

The Bishopsgate Towers include two 65-storey residcnli.il skyscrapers, and ,1 50-storey office and hotel associated with a convention centre.

The residential lowers .no sited on the southern edge of a new Market Square, which Includes .1 linear shopping complex with rel.11! outlets cafes/restaurants, aits and crafts ccntrc and studio workshops, forming .1 new cultural hub foi the neighbourhood

The residential towers share .1 common plan-form, which lus ,1 radial configuration with the apartments forming a 'fan' arrangement on the northern and southern faces I lie peripheral accommodation encloses .111 Internal atrium, which rises through the building surrounded by .1 continuous landscaped ramp I Ins primary pedestn.in circulation forms the principal element of the lowers, which me essentially radial-spiral forms 1 he landscaping ol the atrium is augmented by planted facades and terraces, which collet lively contribute to the rehabilitation of the site, which Yeang defines as a devastated ecosystem

The mixed-use facilities extend over several levels from the base, and occm again «'I vertical intervals such .is level 23, which Yeang describes as .1 High Street, with shops, cafe and pub Taken together, the range of mixed uses proposed is extensive, and Yeang has assembled this into .1 horizontal and vertical toning diagram, which controls the occupation of the multi-layered and multi-level zoned masterplan of the entire building, conceived as a vertical land use pattern This Includes car-parking, vertical services, landscape, retail, housing and circulation The housing Itself includes both social/subsidised and private apartment accommodation, which provides each unit with ,1 planted terrace/garden throughout a range of various plan-types

As thoroughly conceived 'green skyscrapers', these towers exhibit all the major systems of Yeang''. ecological design method, similar In principle to the EDITT tower, but 1 modified to a temperate climate with sustainable objectives applied to a high-density scheme Outstanding amongst the,.« design studies arc Yeang's passive low energy responses Characteristically, the overall form is governed by the sunpath of the site, and the conditions of the summer and winter wlndrose ts entially each tower Is configured as two blocks with .1 weathei-protected landscaped core The buildups .ire orientated "... to maximise solar gain into the Interior spaces In winter and mid-seasons, and io maximise solar shading in 'I summer months". '

in. lllshopsgitte Vowels',


,rnl.al lands.,nuil '<""!> wh«b s,n.als up the Architecture Foundation (In asso. latlon With) Peabody Trust ft.itnh Steel (sponsor) location OlsliopsKatrGoodiya.fi. London Boroughs of Hackney * Tower Hamlets, London M latitude 'it I N

not of storey« tower 1 f, ) - tfi vtorrys town 1 '»0 storeys dnto start t'JVJ (design) complntion dnto areas (3 towers) total gross area l'i/.(XX) m total net area 117,000 sq m total area ol plantation A i in illation 110,000 sq m sit« area gpprox J 4 hectares (H ■) ,urr••.) plot ratio 1 <i dotlgn ftmturat • the liiirl ..iIMm llir a. ., ■ .,1 .. i use, muni lii.imn sustainable high density settlement I lie design lie.i' addles . | lluse usurs follows

(social tuitalnablllty a. concept Illy In-lbe-sky'

the design takes the model .il i genei.il r* "K» .

n city, svilh its Inherent systems zoning and il

Inlrastructiiir and 'vertlcnilli • il Into skyu taper buildings the ikysciilper line Is seen a. ,i ml .. .in nl the . .1» containing wllhln ilsell Hie inhrient elements ..I .i <itv l«1«■« fc p,nits shops, entertainment irnlris. .ommunlty l.«illtles 'social homing, nieilluni tnsl and high .ml hmising el. llie 'rlly in llir sl<y' concept provides to.

• opportunities lor i.h.iI employment Ihroui:1' nsi both on ground and uppei levels

• i healthy mix ol residents willun llir ..une building Th.ough 'vertical toning', irsiilrnl types ,nr grouped acco.dlng lo Income (datennlned hy then housing affoidablllty) anil accommodation prrtnencrs («Ingle units family nulls, lunuiy aparlments. eti), yrl common Utilities (eg |Kiiks, shopping sheets, fir) air shared

• close proximity to b.isu amenities, su. Ii .is the im,.i gnu r.s store, postal bones, Chemist. etc These ,ur .ill liK.iteil within lite same building

• ,1 lir.iltliy lands.-II«-.! environment, with spatial imigieisHiiis ol pilblli open «pac<- (parks 111 ttir sky) I,, semi private (Ii..nl yard) to private open space! (backyard)

h. density

A population density /Ml penons/he. tan- • " Incve.t in (his proposal by building high-rise Ibis would not lie possible with low o. mi.I >>se buildings c. iisnx

Mintuir ol lestdents from ilillnnil ages Incomes

.Mill family Sliuclu.es ne accommodated by the pi.'vision ol I v.iiirly ol accommodation types SchMI housing, subsidised bousing (two .mil thn-i- tiediiHim typesi single apartments two room apaitnirnls three-room apartments ami penthouses d. uses rhe development will Incorporal» housing, .et.i.i community tacHlties. commercial and Hgbl tadustty bulb .mi ll>r ground level ami up Ihr lowei »be location ol housing In cU.se proximity to employment, retail, leisuie and tommunily facilities will leduie irli.ui.r on public banspoit upen space irqulie.iiriit» / eulslooi »pac» I bit design seeks lo X crate conditions on Ihr ground

ih. sky, with features such as a front and ba.k ,

to. eve.y unll, sha.rd se.onda.y and tertiary land' open spa.es Within g.oup. ol Inmung II«- open spa.* ronne. te.t vla^H llie building

». lelallnntliip to immediate .si""«1

,rnl.al lands.,nuil '<""!> wh«b s,n.als up the design |»oposal (uisrtl lieir ins lude* high level bridging over Ule suliuuiwling «Heels and radii fcmou.Hl««OV.. esislMig IM". viailiul

"lu.es (Ii. ules physical

ia,lw»y bask ««I anHaHo«« lire mulll direitlona) sunnevllons , (be SII. to. |H-slrsl.u.'« and syil's»

towel s sandwich shop intermediate garden 'squares'

rain collection pan incxd

intermediale garden 'squares'

launderette pub mini market IT knowledge centre bank

Intermediate garden 'squares' retail, general pub library / bookshop hardware store Intermediate garden 'squares'

sandwich shop oxfarm retail, general academia restaurant

public parks (commons)

in the sky

sandwich shop intermediate garden 'squares'

private front and back gardens launderette pub mini market IT knowledge centre bank

Intermediate garden 'squares' retail, general pub library / bookshop hardware store Intermediate garden 'squares'

sandwich shop oxfarm retail, general academia restaurant rain collection pan pub mufc - Layered environmental moderator creche restaurant photovoltaic panels incxd bud

g ratio o< Affordable howsmg ,0 market-«», houung

The proposal adheres to the design bnef fto^mamons for the foAomng n*fMnum prr . wons foe too« «id H oioig^j

Housing mu

environmental sustainability

ISee pages 64-65 of Yeang K 1999 The Creer Skyscraper Ptestel iM»»»ch. Germany] 1

Key Pin

masterplan and section in th-s case, the lift cores are positioned on the north-east and »\est facades providing a buffer of solar protection in summer. Converse v aunng the winter months, low-angle sun can penetrate to tte ardscaped circulation atrium, and south-east facing residential units receive maximum solar gain. Beyond these basic principles, 'eang has appi.ec special attention to the facade design and the 'e.£bonship of this in particular, to the residential accommodation.

Essentially the facade is designed to allow maximum light into the nte-^r spaces, while excluding cold winds by the use of a multi-layered external wall, which controls both the individual garden terraces and living units. This detailing includes both mesh-screen » "d-breaker elements that reduce the inflow of strong winds, together with adjustable, insulated shutter doors that retain internal "eat at night. This arrangement is then supported by both large aouD e-glazed windows and internal shutters. Finally, there is the contribution of the landscaping and planting, of private gardens and corr-r^nai sky-parks, that both acts as a wind buffer, and in summer as protection against solar radiation.

Seen as a whole, the detail design of the residential unit types -such as the three-dedroom duplex, which incorporates ramps between ievels - all contain a great vanety of articulated spaces and •nnovatve installations, and are flexibly suited to all occupier categories

Whiie Yeang has typically expanded many other overall design considerations such as the ventilation variants incorporating the central atrium the use of south-facing photovoltaic panels as a rain-screen or the rainwater catchment scallops - all part of his P«n agenda it is the additional detailed design of the residential e4ements that particularly marks this protect In turn the careful «^'de - on c- occupation and lifestyle contnbutes a further level 0T cc "eang's ecological architecture g ratio o< Affordable howsmg ,0 market-«», houung

The proposal adheres to the design bnef fto^mamons for the foAomng n*fMnum prr . wons foe too« «id H oioig^j

Housing mu

environmental sustainability

The approach to envwonmental sustamabMy here n a holistic approach « it takes «ito account the entirety of the systems and functors of the ar.ixent errvror-ment

It is contended that eraopca1 dnfcn must consider the fofcmnng aspects of a buWm*

• Its erterro: interdependences, consisting of the system s relations to Us external enwuranei« ««d eowvgenis

• its internal interdependences. be*ig the oesignre mtn's internal relations, activities and operations

• lb external-txxstenwrf exthar^es of energy and matter -being the designed system s nputs of energy and maten*

■ Us mtemal-to-extemai exchanges of energy and mane? -bemg the designed system s output of erwgy anc ma^-is

ISee pages 64-65 of Yeang K 1999 The Creer Skyscraper Ptestel iM»»»ch. Germany] 1

a. external dependencies the site's ecosystem in consideration of the external ecosystem and mwmuM -terdeoeTKienbes of 01? designed svster- we start t* tootang at the site's ecosystem and as c®ooeoe- t 5 endent that ths site is a tota»y u-tarced ano lero culture site "He vtr ~s essentia»? a devastated ecosystem with «tie at as arur-f toe sod flora and fauna remaeur^

The design strategy then 8 to increase bod<vers.r> am organic mass by nevegetabng tie site t order tc er«ibu4a* the site's ecosystem This s aodiesseo by our prove«» or a parv over the land and the adopbon of a system & conbrajous planting up the towers »as verbca -indscapmg'

b. internal dependencies: be ding s operational svstems internal -terdepenaenews -«ate to bunamss ewn onmetel operabonai systems

There aie four eves o> ponDn «or ntemai erv hanenM operabe-i1 systems

• passive mode Oe km-enogv cses^r «AM We use at a^r electro-mechancai systems)

• mixed mode Oe partnly etecW-mechancaK assisted systems that opbmr* other ambler» c nerpes of tie Oca-tv -

• fu* mode Ge acbve tfOtms «•*•• <ow ener© and low environmental inputs)

. productive mode Oe systems ««at generate on-sn* energy. eg photovoltaic <ystr~s>

Our de*gn strategy must be to ma»m« the uwge e-paswe-vx* «-stems (because of a cwest « consumption). w*h the «»» » *

Key Pin ecological strategies

Ecological design starts with looking at the site's ecosystem and its properties Any design that do not take these aspects of the site into consideration is essentially not an ecological approach.

A useful start is to look at the site in relation to an 'hierarchy of ecosystems' (see right).

From this hierarchy, it is evident that this site is an urban 'zero culture' site and is essentially a devastated ecosystem with little of its original top soil, flora and fauna remaining. The design approach is to rehabilitate this with organic mass to enable ecological succession to take place and to balance the existent inorganicness of this urban site.

The unique design feature of this scheme is in the well-planted facades and vegetated terraces, which have green areas that approximate the gross useable-areas (ie. GFA <8 42.820 sq m) of the rest of the building.

The vegetation areas are designed to be continuous and to ramp upwards from the ground plane to the uppermost floor in a linked landscaped ramp. The design's planted areas constitute 40,700 sq m which is @ ratio 1:1 of gross useable area to gross vegetated area.

hierarchy of ecosystems ecosystem hierarchy site data requirements ecologically mature ecologically immature ecologically simplified mixed artificial zero culture complete ecosystcm analysis and mapping complete ecosystcm analysis and mapping complete ecosystem analysis and mapping partial ecosystem analysis and mapping partial ecosystem analysis and mapping mW

i design strategy mapping of remaining ecosystem components (eg hydrology, remaining trees, etc )

mMct are«

• increase biodiversity

• increase biodiversity "

• develop on low-impact areas

1 increase biodiversity ' develop m areas of nonproductive potential > rehabilitate ecosystem

• increase biodiversity and <xgar,< r.«, « rehabilitate ecosystem continuous landscape circulation system continuous landscape circulation system

energy and materials input: production mode concept installation of wind generators on the roof (option)

• site Oe the roof) Is lerrnrd as ■.deal1 for the. type of application located in city surroundings Optimal or.entat.on is 220" due north, as the maiority of the prevailing winds come from this direction

• The most widely used wind turbine types (>e most economically feasible) is the upwind, three-blade horizontal axis type whether the rotor spins in front of the tower about a line parallel to the horizon The vertical axis primarily lift type turbines, as the Darrious model shown on the sketches are not so efficient in energy production and their use can be justified as an architectural element of the integrated design for this building

• To obtain sufficient power from a single turbine (50 kW<), typical dimensions of the main mast and the blades are 30 m and 10-15 m respectively, making this type of application unsuitable for the site

• Small wind turbines (6-10kW) have dimensions of up to 4 5 m (blades), making them more suitable for the Bishopsgate towers In addition, most applications use tail vanes to point the rotor into the wind

• For obtaining approximately a 1 % of the total annual building.

• Load (70MWh), the following two combinations may be chosen 7 x 6kW units at 10,000 Mwh/unit or 5 x 10kW units at 15,000 Mwh/unit

• Strong, rigid supports required to protect installations from strong gusts of wind

• Noise can present a potential problem, as it can be in the range of 35-45 dB

• The payback period of the wind generator is approximately 23 years photovoltaics

Photovoltaic s can be used to achieve greater energy self-sufficiency

An assessment of the environmental options for the two 50-storey mixed use residential towers are as follows

Annual building energy use _

type housin« I 22990 i 200

Figures based on 'Good Practise" energy use in the building from Its owners

Installation of PV cells In SE facade

• Optimal positioning of PV cells South oriented, lilted at an angle of Vf

• For this project Either cover the whole SW facade of Ihe inclining ramp (ash shown on sketch diagrams) or cover the whole SE vertical face of the building envelope, tilted at a 30" angle, av shown on the diagram provide (panel strips placed on low level of each storey foi the whole facade)

• Taking the second case, as the one covering a larger area, total area covered

• Potential power output, assuming PV cell efficiency ol 13% 100 kWp (kW peak)

. Potential energy generation from an 100 kWp source, assuming no shading from surrounding buildings, optimal orientation and optimal angle tile /0 Mwli Afler allowance lot surrounding buildings and actual positioning of panels (Sf instead of S) MMwh

. this «.presents 0 7% of the lolal building load

. Cost estimate i 500.000. assuming the cost ol panels at «.OOO/kWp of installed pown

. Ihe payback period of Ihe PV installation <ar In ,«<■••-•- of Ihe HI«' expectancy ol the unils making Ihelr Installation an uneconomic tolulJort

. Mi.w.«r, tills 1» provided as a d«mon»tratlon ol Ihe productive .node option foi this building

! energy : annual energy i <kWh/m2) i consumphon(MWh)

c. external-to-Internal exchanges of energy and matter (the Inputs of energy and materials to the buildings)

This includes the embodied energy arid ecological .mpact n1 Ihe use of energy and materials in the bu.ldmg. wWh reflect-, the impact of production of the matenal or component (both globally and locally) at the source of manufacture, as «el* as the chain of activities leading up to its delivery to the construction site and it's eventual recycling 'at the end of its useful life)

The initial design strategy is to select materials based on their potential for reuse and recycling in order to 'educe the impact on the natural environment and to positively reww. restore and enhance the natural environment Pnonty r. given lo materials that have been previously used (ie 'waste' from an earlier structure) or that have been recycled This immediately lowers the overall embodied energy figures in the building's mass d. Internal-to-external exchanges of energy and matter (systems output) (management of outputs into the environment)

This includes consideration of waste production and disposal in the life cycle of the building

A central objective of our design method n to limit -.he quantity of materials and energy expelled by the building into the environment In the selection of maten ah. we should avoid use of materials which pollutes the environment

Other aspects considered are the reuse and recycling of building parts and building materials at the end of the building s useful life, and the management of consumer wastes dunng the use of the building (eg through the use of a waste separator for waste recycling, etc )

! energy : annual energy i <kWh/m2) i consumphon(MWh)

output and recycling: water recycling and purification water collection and recycling system

rainwater purification system

key areas summary (tower A)

• housing total net area 22,990 sq m

• shops and others total net area 8,660 sq m

• housing units breakdown

• subsidised housing = 28 units

• Market rate apartments 109 units

• Total = 178 units building population a housing population:

Population © 2 rooms (average) per unit x 2 persons per room x 178 units = 712 persons b retail / commercial population

• nett retail/commercial area = 8.660 sq m

• population @ 1 person per 10sq m net area = 866 persons c total population (per tower) = 712 + 866 = 1,578 person-, water recycling

Water self-sufficiency (by rainwater collection) in the tower is at 2 9V (Note Recycling of grey-water will further increase the water sell-suH.r^ncy;

• Building population = 1,578 persons

• Water consumption = 60 litres/day / person

• Total requirements = 60 x 1.578 persons

= 94,680 litres/day = 94.68 m' per day x 365 day = 34,558 m' per annum

• Total rainfall catchment area = 1,200 sq m.(roof) + 500 sq m

• London average rainfall/annum = 0 593 m

• Total rainwater collection = 1,008 m per annum

• Water self-sufficiency from rain water collection = 1,008 * 34,558 x 100% = 2.9%

water purification

Rainwater-collection system comprises of 'roof-catchment-pan' and layers of 'scallops' located at the building's facade to catch rain-water running off its sides. Water flows through gravity-fed water-purification system, using soii-bed filters.

The filtered water accumulates in a basement storage tank, and is pumped to the upper-level storage-tank for reuse (eg for plant-irrigation and toilet-flushing). Mams water is only here for potable needs.

raw (underground) water

Another, topical, addition to the rainwater / greywater system could be the addition of a raw water. With London's deep aquifer water level nsmg at an alarming rate it would be a responsible move to use some of this water for toilet flushing, etc. Investigations would of course be necessary to establish thai a borehole could provide sufficient yield notes:

The nature of the building generally suits greywater reclamation quite well, although peoples acceptance of using greywater may prove a bamer Greywater can only be stored for a short time (it actually turns septic faster than ttadn"» The storage would therefore be based upon a 24-48-hour turnover, although mranatf could be stored separately for longer penods allowing for the volume that would Se necessary in order to maximise the water captured from infrequent rainfall

• It is estimated that the demand for greywater would be in the region of 31.000 V day lor each of the two towers A separate rainwater collection tank in the tg«*'0 3x3x2 m or equivalent capacity would be recommended in coniunctwn wth the W'9 greywater storage of approximately 4*4x2 m and treated storage of 2x2*2 m

passive low-energy responses

Sky Parti provides Recessed Shading Summer

Sunny Nonh-East Facing Apartment

». by building configuration

The building is configured as two blocks with a weather protected central landscaped core b. by building orientation

The building has been orientated to max.mise solar gain into the interior spaces in winter and mid-season-, and to maximise solar shading ,n the summer months

• lift cores are located at the north-east and west facade-, of the building to provide solar protection in summer

• during the winter months when the sun Is low central landscaped circulation area and south-east units receive maximum solar gain c. by facade design

The facade is designed to allow maximum light into the interior spaces while keeping out cold wind-, by mea-^ of a multi-layered external wall with

• wind breaker mesh screen to reduce inflow of -.trong winds

• insulated shutter doors to retain building heat at night

• large double-glazed windows

• internal shutters.

d. by landscaping and vegetation

Vegetation and landscaping within the private gardens and sky-parks building act as wind buffer while giving user; a more humane environment.

In summer, vertical landscaping acts to obstructs, absorb and reflects a high percentage of solar radiation thus reducing ambient temperatures The damp surfaces of grass and soil will also contribute to a cooler and healthier building f ener9y & materials Input: Passi^ energy responses (tower A)

passive low-energy responses

The design here starts by optimising all the passive mode opportunities <le optimising the use of ambient energies of the locality) in relation to the temperate climate The pass™ methods used are as follows sunpath of site

Heal Recycling mixed-mode system

building configuration

Summer Wind summer Windrose winter Windrose

Wind Breaker on South West Facade

Pholovoltaics Panel On the South-West SOe as Solar Coiieciors

Winter Da»

composite of buffer

-West-East -Elevator Core as Solar Butter

Protected Internal Landscaping Park energy & materials input: mixed mode concepts

mixed mode concepts

The basic mixed-mode strategy employed here is to encourage natural ventilation during the summer and mid-season months when the outside temperatures are conducive, and in winter, to minimise energy losses and changing over to a mechanically assisted ventilation system

The exterior facade for the apartment units is considered from both the bioclimatic as well as an aesthetic angle for the city of London environment The facade is multi-layered The outermost layer is a moveable wind shield of perforated metal mesh, which can be opened to improve ventilation where required Next are timber folding doors which may be shut or angled to keep the terraces shielded from the sun in summer yet allow views out

The third layer is double glazing for improved insulation properties And lastly, all apartments are specified with adjustable timber blinds tor further heat insulation

On a windy winter day. the wind shield is drawn but due to the low altitude of the sun. the rays penetrate the perforated mesh and on through the opened mtenor blinds.

On a cold winter s night, all movable layers air diawn. allowing highei heater efficiency

On a breezy summers' day. the windshield and glass doors are opened to allow breeze into the apartment while the timber folding doors allow only desired sun to enter through the opened glass-doors, thus allowing the teirace to be enjoyed The movable floor grating is also removed for inter-floor cooling the metal mesh acting as sun shields

On a hot summer night, all layers aie open for maximum natural-cooling and cross-venWaUon

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