Photovoltaic Design Integration at Battery Park City, New York

This paper is a study of the photovoltaic (PV) systems in the buildings' design of the Battery Park City (BPC) residential development, in New York. The BPC development is the first in the US to mandate, through the 2000 Battery Park City Authority (BPCA) guidelines, the use of PV as a renewable energy generation system in its individual buildings. The scope of this study is to show how PV is integrated in the BPC buildings' design process, and what can be learned for future PV applications. The study draws directly from the design decision making sources, investigating on the concerns and suggestions of the BPCA director of sustainability and the BPC architects and PV installers. It attempts to contrast a theoretical approach that sees PV as a technology to domesticate in architecture and bring, through grounded research, PV industry closer to the architectural design process. The findings of the study suggest that while stringent environmental mandates help, in the short term, to kick-start the use of PV systems in buildings, it is the recognition of the PV's primary role as energy provider, its assimilation in the building industry, and its use in a less confining building program that allows for its evolution in architecture.


Introduction
PV cells transfoml the visible spectrum of solar radiation (photons) into electrical energy.The greater the efficiency of the PV cell, the larger the PV surface area exposed, and the better the PV's position in respect to the sun, the greater the total electrical output produced.
lt is important to remember that initial use and testing of PV cells occurs in space.In 1958, PV cells were installed in the satellite Vanguard to generate energy to power its radio transmitters.The event was significant because it demonstrated the original scope and potential of PV: to effectively generate self sufficient energy from the sun.This machine-like quality of PV remains fundamentally unchanged, and is arguably what challenges architects when PV systems are to be integrated in a building's design.The integration of PV in architecture can potentially provide an important supply of eJectricity for a building's energy demand and significantly contribute to the reduction of carbon emissions.The application of PV systems in the BPC buildings represents a challenge that architects face globally when presented with PV technology: to make PV perform, and assimilate it as constituent part of the design process.This paper explores how PV systems are integrated in the design process of the BPC buildings.The scope of this paper is to show what can be leamed from the BPC experience for future PV application in architecture.The paper begins with a review of PV in architecture.lt then gives a background of the BPC development.The main body of the paper discusses emerging themes stemming from the architect's integration of PV in the BPC building's designs.Finally, the paper draws conclusions on the application of PV technology in architecture.

Research method
The source material of this study is from on-site video interviews carried out in the period 30/9 -11110, 2009, with the BPCA director of sustainability, the architects in charge of the buildings concemed, and the BPC PV installer.The raw interview data is transcribed and subjected to content analysis to show emerging themes in the integration ofPV in the building's design.The content of each theme is interpreted through observation and literature review.Conclusions are drawn on the findings, and suggestions are made for the integration of PV in architecture.

PV in Architecture -A Review
Literature on the application of PV in architecture is easily accessible and rapidly growing.This is particularly the case for practical manuals and handbooks (Thomas, 2001; DGS, 2005; Gaiddin, Kaan & Munro, 2009; Krawietz, 2010;  Weller, Hemmerle, lakubetz & Unnewehr, 2010) that provide architects with design guidelines and case studies for integrating PV in their projects.However, for an updated view of the synergy between solar energy, PV industry and arehitecture, and a better understanding of the forees in the implementation of PV in architectural design, we must refer to the International Energy Ageney Photovoltaie Power System (IEA-PVPS) programme surveys (lEA-PVPS, 2008) and annual reports (IEA-PVPS, 2008;2009).
Established in 1993, the mission of the IEA-PVPS programme is to accelerate and promote the development and deployment of PV solar energy through information dissemination and a set of seheduled tasks.The programme's premise is that of PV as a sustainable renewable energy source that can signitieantly eontribute to the reduetion of earbon emissions and world dependeney on fossil fuels.Central issues relevant to the introduction of PV in buildings, accountable for more than 40% of the world's energy demands, PV economy, government ineentives, and technologieal innovation.In support ofthe advantages of integrating PV in buildings we find studies, from both IEA-PVPS programme and independent soure es, which focus on the PV's eeonomie, environmental and arehiteetural added value (Oliver & Jaekson, 200 I;IEA PVPS, 2002b;2002c;Marsh, 2008).
Within the IEA-PVPS programme tasks, Task7 (Schoen, Prasad, Ruoss, Eiffert & S0fensen, 2001) and Task 10 (Gaiddin, Kaan & Munro, 2009), are particular to the implementation of PV in the built environment.More specifieally, the goal of Task 7 is to enhanee PV's architectural and technical quality and its economic viability in the built environment, as weil as removing non-technieal baITiers (such as administrative and market related), while that of Task 10 to enhanee wide-scale, solution-oriented photovoltaic power production application in the urban environment However, the issue of PY architeetural quality, which according to the author of this paper is at the heart of the architectural design process, is treated only as a subtask ofTask 7 (subtask I).
Subtask 1 is specifieally aimed at providing architects with a set of criteria for successfully integrating PV in arehiteeture (design criteria for good quality PV-projects), with guidelines on how PV ean be incorporated in the building design proeess and a database of notable PY applications (IEA-PVPS, 2002a).While recognizing the difficulty for PV technology to be fuHy ineorporated in the design process, Kaan & Reijenga (2004) underline the value of Task 7 arehitectural eriteria as a starting point for arehitects to orient themselves when integrating PV in their designs.The argument is that, beeause PV is not an indispensable material in architecture, it i5 seen by architects as an add-on element and in need of an organized set of criteria.The view of PV as an added element of architecture is evident in reeent pubJications (Bahaj, James & Jentsch, 2007) and, as will be shown, reinforeed by those directly involved in the design deeision making proeess.
The prevailing approach to PV's integration in arehiteeture, however, i5 top down.ft starts from the PV industry, and the powerful arguments that support it5 proliferation, and pushes towards its acceptanee and incorporation in architecture.By contrast, the author of this paper would like to stress on the importanee of the eontributions that go from the design proeess experienee towards PV industry.In this direction, and non-withstanding the specificity ofits location, the BPC development offers a unique opportunity of investigation.At BPC, within a framework of time, building program, and site, architects, PV installers and real estate developers, are cal1ed to respond to the introduetion of PV as mandatory requirement.This results in diverse design approaches and emerging themes that are perhaps a call from the world of architecture to that of PV industry.The idea of the BPC development starts in the mid sixties, following the demise of the shipping industry and the progressive decay of the piers jutting out onto the river.This vast dysfunctional area on the waterfront was seen by the then ex govemor ofNew York, Nelson A. RockefeIler, as an opportunity to have full jurisdiction over buildable areas and, through the strategy of reclaimed land.start an entire new city jutting out from Manhattan lsland.The development of BPC goes through two distinct phases that are visually experienced with a visit to the site.The first goes from the mid sixties 10 the new master plan 01' the 1979.It is defined by several master plans that result in closed communities such as the Gateway, which shows c1ear traits of excJusion to street vitality and nature.The second phase sterns from the 1979 master plan.This phase begins to include environmental considerations, primarily at an urban design scale, and can be considered the reference driver for the rest ofthe BPC development.
[n 2000, the BPCA establishes the Hugh Lucre Residential Environmental Guidelines (BPCA, 2005).The formulation of the guidelines is coeval to the Leadership in Energy and Environmental Design (LEED) Green Building Rating System (USGBC, 2010).It distinguishes itself from LEED, however, by setting mandates, rather then options, with stringent requirements for the provision of renewable energy and green power sources.The guidelines mandate that renewable energy sources be incorporated in the BPC building's design to initially provide 5% of the base energy load of each building; that is: the load of the buildings' non-tenanted spaces.Several studies are conducted to explore the different renewable energy options, including wind and biomass.The application of PV systems, however, quickly appears to the developers as the most tested and economic option, and as such it is adopted in the BPC buildings.
The BPC buildings, designed since 1999, represent a test-case in PV application.For the scope ofthis study, the buildings considered are: The Solaire (2003), Tribeca Green (2005), The Veridian ( 2006), The Millennium Towers (2007), The Riverhouse (2008), The Visionaire ( 2008) and Liberty One and Liberty Two, also known as 'Site 23 and 24' (under construction).All the buildings follow tight zoning and geometric constraints on massing, orientation, and envelope directives (i.e. the ülyade's ratio of opaque to transparent).

Emerging Themes
The emerging themes are categorized in 4 sections, namely: The 'carrot and the stick' (discusses the effects of mandating PV systems in the BPC development); PV and building integration (discusses the architecl's different approach es to PV integration in the design process); PV industry and design process (discusses the difficult relationship between PV industry and design process); Green visible (brings out the PV overall prevailing function at BPC, comparing the short term semiotie funetion of PV with its potentiallong term goal).

4.1
The 'carrot and the stick' Residential development is an exceedingly money eonscious seetor of the building industry.New built residential buildings must generate a certain pre caJculated return, and anything outside of a tested financial program is seen with scepticism, and as a risk.Direetor of Sustainability at the BPCA Susan Kaplan, states that having mandated the use of PV as renewable generation system through the BPCA residential guidelines has fostered the development of the PV industry in the residential seetor (Kaplan, 2009).According to Anthony Pereira (2009), President and CEO of AltPower, the BPC PV installer, "the reality is that if you did not use the stick, no one would apply the technology, no matter what the incentive.The stick had to happen for it to happen".For the scope of this study, the question is: what effect did the mandatory inclusion ofPV have on the BPC architects and developers?

The stick
From the interviews carried out on the buildings under investigation, the architecCs general consensus is that, were PV systems not required through regulation, they would not have been considered in the building's design.The project manager ofthe Solaire and the Verdesian buildings (see Figure 2 and 3, and Figure 5) goes as far as stating that no one in the design team would have spontaneously considered PV, and indeed any on-site renewable energy source, as an option to promote green design (Hesse, 2009).Overall, the BPC architects welcomed the PV challenge, but saw it more as part of a programme to carry through, than a design challenge.There are multiple reasons that perhaps explain this sentiment.Firstly, the requirement tor the PV to provide 5% of the base building load was seen as minimal, and inconsistent for a full engagement of PV into a comprehensive design project.Secondly, overshadowing studies showed that solar access was limited to specific fronts of each building, limiting the architect's design options in terms of PV loeation and positioning.Thirdly, the building's fixed massing, orientation, and envelope requirements prevented any real spatial eontribution of the PV to the building's form.Under these terms, it could be assumed that PV was not spontaneously considered by the architects because it hindered the very nature of the architectural design process: at the design eonceptual phase, there was limited scope for PV becoming a participatory element of the design, and PV systems tended to be considered as an add-on element.From a developer's perspective, independently of economie reasons, PV represented a risk.Real estate developers tend to otTer buildings that are as neutral as possible to increase the range of potential clients, and there was no precedence to show how NYC clients would respond to a PV c1ad building.

The carrot
It is suggested, however, that it is the very challenges posed by the introduetion of PV in the city, and the stringent building and environmental guidelines set by the BPCA, which has triggered a set of attraetive advantages tor architects and developers.To begin with, architects were prcsented with the opportunity to show their commitment to green building design and promote their practiec as environmentally responsible in a highly visible way.BPC has also shown to be an incubator for the use of PV in the city.There is evidence that it has drawn architects and developers to use PV in their future projeets, and engage in the use of PV systems with more confidence.An example is the Helena building in New York by Fox and Fowle architeets, completed in 2005.As PV installer of the Helena, Anthony Pereira states that the decision to include PV in the building's design agenda was toste red by the physical evidenee provided by the BPC buildings, bringing forth referenee and eonfidenee to the PV initiative (Pereira, 2009).Likewise, the Albanese Developing Corporation.developer ofthe Solaire, the Verdesian and the Visionaire has, since their experience at BPC, started to incorporate green buildings strategies as a norm, with the incJusion of PV in most of their projects.Most importantly, BPC has enabled to trigger govemment financial support and tax breaks incentives, making the inclusion of PV in buildings' more attractive, expanding the use of PV in architecture and pushing for innovative solutions.

PV and building integration
The definition of a building integrated PV system (BIPV) is that of an energy generating PV surface that also takes on the function of architectural envelope eomponents required in a building's system.Such functions could be, for example, insulation, rain sereen, or a shading deviee.At best, a PV assembly can serve, besides the energy requirements of a building, many arehitectural functions combined, offsetting the total cost of a building construction.A full integration ofPY in buildings is arguably one, however, where PV is assimilated in the design proeess and becomes a eonstituent part of a building's resolution.The BPC architect's address this issue in different ways.In doing so, however, they show evidence of a split in the Py's potential role as efficient energy provider, building component, and aesthetic complement.Shown below an excursus ofthe buildings considered in this study.

The Solaire
The Solaire (see Figure 2 and 3) is the second building in New York City to integrate PV systems (the first is 4 Times Square).The Solaire's projecl manager describes how sunlight geometry simulation studies showed the Solaire's PY eftective surfaces limited to the building's west fac,:ade, overlooking the Hudson river, and to the building's bulkhead (Hesse, 2009).In these two zones.the design approaeh to PY integration is notably different.In the west fac,:ade, the custom-made PY panels are designed as building cladding.In energy terms they benefit from the aftemoon sun and its reflections bouncing off the river.Their prevailing function, however, verges towards an aesthetics tour de force, with the unprecedented challenge of relating the building's PV facade to the public at pedestrian leveL The PV systems in the Solaire's bulkhead are, by contrast, off-the-shelfmodules.They complement the energy requirements set by the BPCA, and are less involved in an aesthetic pursuit.The Solaire's west facade shows the effort to construct and visually integrate PV in the building.This design tension, however, falls into the more profane, machine-like quality of the PV in the bulkhead, there to satisfy the building's energy requirement, highlighting the difficulty in making BIPV a constituent part of a comprehensive, all round design resolution. 4.2.2Tribeca Green, Millennium Towers, Site 23 and 24 These buildings (see Figure 4) are designed at different intervals during the BPC development; they show, however, similarities in their design approach.The PV systems are applied to all of the buildings' bulkheads.Besides meeting the energy requirements, the PV panels serve at most the additional function of rain sereen, as in Tribeca Green and the Millennium Towers, or as eanopies, in the Site 23 and 24 buildings.From: BPCA archive.
Considering that PV application needs to be subjeeted to building regulation approval, and any variation that goes beyond tested solutions faces uncertain realization, the design approach of the above buildings i8 non risk taking.Onee the energy requirements are met, and a satisfactory aesthetic solution is achieved, there is no further push towards finding innovative ways to include PV in the design proeess.Such approach is stressed in the Site 23 and 24 designs, where the architects ensure an effective applieation of PV, by working baekwards: starting from considering what would meet the BPCA requirement and building regulation (Kaplan, 2009;McCormack, 2009).In the Millennium Towers, PV panels are plaeed on the roof top as with a PV stand alone system.suggesting disengagement to the building's design composition process.

The Verdesian
In the Verdesian building (see Figure 5) the custom made PV panels cover the south and wesi of the building's fayade.Besides generating energy, their additional constructional role is of rain screen for the mechanical rooms.It is important to note that the architects of this building insisted on maintaining the vertical mullion aesthetics on its west fayade.The bulkhead's ventilation vents are for that reason located in the south fayade, reducing the area of PV southem exposure and consequently the PV system energy potential.A sign of the aesthetic and compositional importance given to PV over PV energy production, which brings forth the question: why not generate energy efficiently, as a prerequisite?

The Visionaire
The Visionaire's PV custom-made panels (see Figure 6) aci as a full cladding system, incorporating a ventilated cavity to avoid heat build up and loss of PV efficiency.The panels represent an example of leam by doing, gathering from the Solaire's experience where the direct contact ofthe insulation to the PV glass generates heat build up, and incorporating the technological improvements in the building design process.In the Visionaire, the architects maintain the PV panels flush with the fayade.In doing so, however, they rely on a fixed building geometry showing, like in the Solaire building, the domestication of PV to an aesthetic and constructional role.Figure 6: The Visionaire.

The Riverhouse
The Riverhouse (see Figure 7 and 8) is one ofthe last bUlldmgs to be completed at BPC and.perhaps because of thai, one of the most innovative with PV application.The building's large volume and base building energy demands would have required vast PV surfaces.The architects responded to this requirement with a dynamic PV sunlight tracking system in the building's bulkhead, shown in figure 8.The system crowns the building and allows an estimated 20% increase in efficiency when compared to an equivalent solution with fixed PV (Pereira, 2009).Here, the PV does not substitute any architectural building's component.This trade off, however, allows the PV to work freely and to deliver what is arguably their primary function: to effectively generate energy from the sun.
dynamic PV system.4.2.6 PV industry and the design process When the BPC architects were asked about the single most important lesson learned on the application of PV in the design process, the recurring theme is that of the difficult relationship architects have with PV industry, and the need for PV versatility.That has obvious design implications as each solution has to be valuated by local jurisdictions, leaving the approval of each specific proposal of PV integration uncertain.In this sense, the IEA-PVPS Task 7 architectural criteria is perhaps a testimony of the need to find a common ground between what the PV industry can offer and the architects requirement of PV versatility.The confining BPC building program magnifies this issue, showing examples that range from high connection to disengagement.This disengagement can be seen, for example, in the Millennium Towers, where the PV system is placed vertically on the building's rooftop detached from any contribution to the building's architectural design.In other cases, however, there is a strong will to find a common ground by integrating PV into the design process, such as in the Solaire's west fayade.

The case of the Solaire's west fa~ade
The Solaire's west fayade, shown in Figure 2, could be considered as the most important example at BPC of finding a meeting point between what the PV industry can offer as a product, and its integration into the buildings design process.The Solaire's designers were faced with a design challenge that was unprecedented for their office, which also meant dealing for the first time with trade issues on ownership over the installation of the custom made PV panels.The window installers, the iron worker, and the electrician called for ownership and responsibility over the panel's installation.The debacle was resolved by sending each PV customized panels to an offsite window manufacturer who glazed them into a unit.The panels were then delivered to site and installed by window glaziers as window elements and wired by electricians (Hesse, 2009).This non-programmatic way of operating, whose outcome largely seems to be the product of an empirical approach, suggests that we are a still very early phase of PV integration in buildings.Architects and PV producers have to improvise to find 80lutions.During the design development phase, the outcome of the relationship PV -design process is highly uncertain.

PV and glass
Arguably, PV is an unlikely architectural component because it still lacks the versatility of most building elements necessary to compose architecture, such as, for example, a brick or a concrete masonry unit.The best bet of PV becoming one, as the architects and PV installer in this study suggest, is to associate PV with glass.The architects state that: "PV is basically glass, and is to be treated as such ' (Hesse, 2009), "PV was considered as a glass surface" (Rosen, 2009), "we tend to see PV as a glass element" (Bashkara, 2009).The PV installer suggests architects to "consider PV as glass" (Pereira, 2009) In fact, PV is treated at BPC either like an add-on glass panel (Tribeca Green, Site 23 and 24, and the Riverhouse) or like an extension of the glass envelope (Solaire, Verdesian, Visionaire.).Although the glass-PV association presents the apparently insurmountable challenge of allowing for transparency while absorbing light energy, many innovative PV producers are already going in this direction.Tbis study suggests that the main advantage of PV as glass is that it would become an architectural component, rather than a system, greatly increasing its versatility in architecture, and hence its ability to be incorporated in the design process.

Green visible
Ifa PV systems' main purpose is to generate energy from renewable sources and significantly contribute to a building's energy demands, then the PV installed at BPC need to be put into question.In fact, the BPCA 2000 Guidelines requirement to provide only 5% of the base energy load, updated in 2004 to 0.75% of the building's base energy loads ca1culated on the actual PV energy produced, is a small contribution to a building's energy demands, particularly when compared to the estimated energy potential of BIPV.To put things in perspective, based on a IEA-PVPS report, it is estimated that ifbuilding surfaces are used that generate 80% of the maximum solar power, the ratio between BIPV solar electricity production and current electricity consumption can vary from 15% to almost 60% in IEA countries (Schoen et al., 2001).
At BPC the PV's purpose ofrendering the buildings' green agenda visible to the public predominates.This intention is already present in the BPCA guidelines (BPCA, 2005) which state: "Where appropriate, strongly consider using BIPV in locations that are highly visible to the public" (p.ll).PV is evidently considered the primary tool for conveying the green message.This is reinforced by Kaplan (2009) who states that PV is "the only renewable energy system that can be seen and understood by people [ ... ] showing to the public a clear wish to be less dependant on non renewable energy sources".The BPC development, however, provides no single comprehensive visual design strategy.According to Kaplan, developers were "required to integrate PV without aesthetically knowing what directions they wanted PV to take them".Tbe design approach in the BPC buildings is highly diversified: it goes from a fulI commitment to PV integration within a building's aesthetics, to simple PV labelling.These two extremes, and the variations in between, are discussed below.
4.4 Tbe!wo extremes: tbe Solaire and Millennium Towers In visual terms, the Solaire stands out as the most experimental, risk taking ofthe BPC buildings considered in this study.The visual engagement of PV starts at street level, with the embedment of PV cells in the entrance canopy, and continues upwards on west fayade with the colour variation of the recycled Intel chip cells.There is, in the Solaire, an attention to scale and visual perception.At street level one can see the single PV cells of the canopy, trom further away the electric blue panels blend in the west facade.In the Millennium Towers, by contrast, the PV cell array is out of visual reach from the city.Being on the building's roof top and facing west, the Millennium towers' PV system can only be spotted from an aerial view, as shown in Figure 4b.The design approach in the two buildings goes to the two extremes: fully committed to engage the public in the Solaire, satisfied with just confirming the PV energy requirements in the Millennium Towers.

Variations to the green visible theme
The architect's push towards a green manifesto is weil seen in the Visionaire building.Kaplan describes how, during the building's design development phase, the Visionaire's architect's wanted to change the PV colour, from black to blue, and how this would have meant increasing the PV blue cells surface area (to obtain equivalent energy output).It is important to note that the architect, initially resisted to satisfying that revised surface requirement (Kaplan, 2009).The event i5 significant, because it shows the designer's focus on the PV semiotic role over its energy goaL In the Visionaire, evidently, a symbolic PV blue strip flag sufficed to send the green message.
Tribeca Green, the Verdesian and Site 23 and 24 buildings all come under the BPC building typologies that have to rely on the bulkhead oLthe building to guarantee sufficient PV exposure to sunlight.Tribeca Green "lind Verdesian buildings are, however, the only_ones that can count on a certain degree of visibility from the street level.It is perhaps because of this reason that the incorporation of PV in these two buildings is visually incisive.In both instances the PV stand out from the buildings fabric: jet black in Tribeca Green, electric blue in the bulkhead of the Verdesian, both against the buildings' red brick fabric.The PV of the two buildings must be noticed, even if that means in stark contrast with the buildings' fabric.
In the Riverhouse there is no need to negotiate between PV and building's composition because the PV systems stand out for what they are: a mechanical device, detached from the building's main body.The only compositionallicence in the Riverhouse is the design of fake PV panels in the North fayade to crown the building.In the Riverhouse, there is no detachment between PV aesthetics and function.PV is expressed for what it can offer: a machine-like technology that generates energy.

Conclusion Remarks
The research analysis of the PV systems at BPC has led to aseries of emerging themes.The content of these themes has led to findings that can be of use to a better understanding of the integration of PV in architecture.

The 'carrot and the stick'
Mandating PV in a building's design process can initially find resistance by architects and developers alike.There is evidence, however, that it can trigger a more comprehensive application of PV, and thereby attract its more consistent use in architecture.The application of PV in a rigid pre-constituted building programme (such as the BPC development) limits the contribution of PV in a building's design resolution.The study suggests that greater design potential (ability ofPV to contribute to a building's resolution) and greater scope (a more significant contribution to a building's energy demands) would allow a greater design involvement and accelerate innovation.

PV and building integration
The BPC buildings show that PV can assume three different roles: that of energy generators, as substitute to building component, and an aesthetic complement to the building's composition.In all of the BPC buildings, however, there is a visible separation of these roles, showing the difficulty in integrating photovoltaic technology and architecture.Depending on the architect's design approach, PV verge towards aesthetic goals, their function as building components, or as efficient energy generators.but not all of these three things together.The study suggests that, with the current PV technology offered, by releasing one of the PV roles (i.e. that of substituting a building component) it allows PV to work more effectively.This satisfies what is arguably the PV imperative: to generate energy from the sun in the most efficient way possible.

PV industry and design process
There is a consensus among the architects that the relationship between PV industry and architectural design is a difficult one.In design projects that explore the integration of PV in architecture and push for new solutions, that relationship is still improvised, and the outcome highly uncertain.This calls for a robust programme that will ensure greater control over that relationship while allowing for innovation to take place.PV versatility is key in PV building integration and this can be pursued with PV as a building element.Architects are already considering PV as if it was gl ass, suggesting that this is where the technologicai efforts need to be placed.

Green visible
Together with wind turbines, PV is a commonly recognizable form of renewable energy generation system.This is an attractive incentive for architects and developers that want to convey a message of green involvement to the public.The PV overpowering ability to send the green message with little corresponding substance in energy provision can, however, distract from PV primary function of generating energy.
Overall, the findings of the research suggest that the integration of PV technology in architecture is still at a raw and early phase, and that PV integration as an organic, constituent part of the design process requires a big leap in PV technology.Battery Park city is perhaps an expression of the short term goals of PV building integration.These are: to promote PV in the building industry, to start to learn how to integrate PV in the design process, to render PV green technology visible.A long term goal of PV integration, however, must have as primary moral imperative to make PV generate energy efficiently, and significantly contribute to a building's energy demands.

3
Figure I: Plan of the BPC development and photographs of the site looking south-east (a) and north-east (b).From: BPCA archive.