Beyond Net Zero: Much to Lose by Doing Nothing, and Everything to Gain by Doing Something
Executive Summary
Hong Kong as a city is uniquely positioned to adapt to a new normal and share learnings to other modern cities as they face and adapt to rising climate challenges. Why is this? The combination of local environmental exposure conditions coupled with historically rapid advancements in building design practices and construction technologies mean that Hong Kong has more opportunity than most to take up the mantle as the trailblazer for modern and climate resilient cities. But only if it acts quickly and methodically.
IXO Partners’ in-house studies reveal that while the city’s buildings exhibit remarkable strengths, there is substantial and untapped investment potential across three key areas: real energy-use reduction, real carbon reductions, and real climate resilience. As highlighted by our Managing Partners in public and private forums during 2024, it is imperative for Hong Kong to act quickly to capitalize on these opportunities while adopting a systematic approach to revitalizing the city and strengthening its resilience. Importantly, there also exists an outsized risk: without targeted adaptation, the city risks environmental degradation on a scale which may soon be insurmountable.
This first major opinion piece released by IXO Partners deep dives fundamental truths about Hong Kong and its ability to rise to the challenge of climate change, from the perspective of our founders’ specialist expertise. Entering our third year of business, IXO Partners recognise that our contextual knowledge of the city is not only diverse; it is diverse enough to offer new perspectives on how to re-modernise the city for its inhabitants. In this article, we explore the relatively unconsidered contribution of physical materials in crafting the city’s climate responsiveness and how we expect interdisciplinary science and engineering to fuel Hong Kong’s to strike out as a centre-for-excellence in green investment, innovation, and education.
In short, in this city where IXO Partners is established and in which our founders call home, this article explores how much has everything to gain in taking decisive steps towards responding to climate threats.
Setting the Scene: What is Remarkable (and What Must Adapt Quickly)
Hong Kong was, like many of its contemporaries, built in leaps and bounds. With landmark projects creeping into the skyline in the early 1970s, building construction hit its stride from the mid-1980s and the city grew quickly upwards and outwards, shaping itself into the city we recognise today. Hong Kong is now home to the greatest number of skyscrapers globally (554 no. buildings taller than 150m), with the largest urban population living at or above 15 storeys; and we estimate it is also home to the greatest range of curtain walling technologies spread over 50,000 buildings or more.
To the outside observer, many of the statistics relating to Hong Kong’s built environment are remarkable and unrivalled, particularly considering the significance of its physical constraints: severe typhoons, dangerous rainstorms, limited available land, (historically) unstable slopes. As insiders and engineers, the view is no less remarkable: the city is home to one of the most tightly regulated building industries, with an exceptional framework to protect the city’s inhabitants from building failures in traditionally extreme environmental events.
However, the local building industry regulatory ecosystem which we know intimately, and which enabled such phenomenal transformation, is now so complex and burdened by such contradictory pathways, that it can be difficult to see what can and should be modified safely for the city to respond effectively to climate change.
Compounding the challenge, IXO Partners estimates that Hong Kong has five years at most to fundamentally remodel its approach to building design, safety and durability. At the heart of this urgency resides five very different and intertwined issues; some of these are common to other modern cities, but some are unique to Hong Kong. The five issues are:
Little to nil performative maintenance of existing building stock,
Significant number of buildings operating beyond service life without major maintenance,
Poorly designed buildings from energy consumption standpoint,
Retiring professional expertise,
Increased severity of environmental conditions.
Against this backdrop, the good news is limited but it is of the best sort: our buildings are amongst the most structurally robust in the world, and we have a significant number of them. Strong physical foundations allow us to flex into areas of sustainability considered largely out of reach in most modern cities.
So, with 2030 as our target year, we move now to outlining the real actions IXO Partners advocates to drive measurable impact. Within each of these actions lies significant consideration and study; these are based on our unique lens. Please reach out to us directly for further details and we are happy to share references where these are not subject to non-disclosure agreements.
Driving A Measurable and Systematic Response: Our 9-Point Plan for Hong Kong
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For those of us involved in the design and construction of buildings, there are two significant stages in a building’s life: its design life and its service life. The service life occurs at the half-way point in a building’s design life, meaning that if a building is designed to stand for 50 years post construction, the service life occurs at 25 years. In most jurisdictions, this is the time when major mechanical plant is replaced and the façade undergoes major maintenance, which might include: re-finishing exposed framing, replacement of weatherseals, replacement of thermal insulation, replacement of corroded glazing or other cladding materials.
Buildings in Hong Kong which are approaching or have exceeded their service life were not originally designed for optimal envelope thermal performance, including: solar gains, conductance (thermal bridging), airtightness. For these buildings, there is substantial opportunity for energy-use improvement during a major maintenance phase: in exceedance of 20% with minimal interventions and in exceedance of 40% with major interventions. Our studies show payback periods range from 2 to 10 years depending on capital construction costs. Our top tip: the more spent, the faster the payback.
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Facades on commercial and residential buildings in Hong Kong are subject to significant gross floor area zone (depth) restrictions. With taller floor-to-floor heights in Hong Kong compared to other jurisdictions, couple with higher wind pressures, the impact of restricting the façade zone (depth) directly translates to increased thickness of the façade framing. This issue propagates two issues: (1) it increases the weight of the façade by 20% or more, meaning more connections are needed to the primary structure, and therefore increasing the weight, cost and installation safety issues associated with the façade, (2) it reduces the capacity of the façade system to be thermally efficient or to perform in an appropriately air-and weather-tight manner.
Our in-house studies show the embodied carbon for a comparable façade system in Hong Kong is 30% higher on average due solely to the restricted zone (depth) – i.e. not accounting for material wastage due to cutting away of the frame depth in locations where it clears the structural slab edge.
A relaxation or exemption on GFA through demonstrable energy efficiency design must be incorporated into the building codes to enable a return to safe-to-install, and structurally and thermally efficient façade systems.
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There exist no stringent requirements governing the performative maintenance of buildings in Hong Kong – and particularly not related to façade improvements for air infiltration and exfiltration (air conditioning which is pushed out of the building via pressure differential). Current efforts to reduce energy consumption often involve minor internal improvements and service upgrades, typically with extended mechanical plant shutdowns during non-working hours. These strategies, much like global building design codes, are static and reactive.
Our in-house studies show that minor improvements to weathertightness can relax loads on mechanical plant and reduce the impacts of humidity and temperature cycling which is present (and which contributes to degradation of materials) during mechanical systems shut down periods.
Façade thermal and weather performance audits must be adopted as part of any serious review of existing building performance, with rigour established around testing and expertise of professionals, above and beyond the existing energy audits and mandatory building inspections required by regulation.
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Many buildings in Hong Kong are more material-intensive than necessary, even to respond to more historically more extreme environmental conditions. To turn an issue into an advantage, building heights can be easily extended with lightweight construction. Our in-house studies indicate that it may be feasible to add 10% to 20% of additional Gross Floor Area (GFA) by constructing extra floors on existing buildings – we estimate up to ten floors on average.
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Re-use of primary construction materials in a circular city is a concept considered largely out-of-reach for most other global cities. However Hong Kong as a circular city is entirely plausible due to its high density and prime location to local manufacturing facilities in Guangdong (Shenzhen, Zhuhai). Under-utilised spaces in Hong Kong may be leveraged to bring mini-manufacturing hubs, mini-reprocessing hubs and other temporary laboratories into the city centre, allowing fast re-cycling and re-processing of existing construction materials to re-purpose glass, aluminium, steel and other major materials for use on other building upgrades or for infrastructure. Our in-house studies show that the vast majority of existing materials can be re-purposed in this manner. The additional benefits are obvious: bringing innovation back into the city centres, which in turn drives deep expertise and education of building construction technologies, enabling rapid transformation to a traditional industry.
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Current new build, retrofit and decarbonization strategies in Hong Kong are siloed and while they may address today’s (or yesterday’s!) climate conditions, they do not build in a systemic response to the additional and dynamic environmental design loads and stresses being placed on our buildings due to increasing incidence and severity of climate conditions – with longer summers in Hong Kong bringing hotter days, higher humidity, higher velocity winds, and more rain.
To maintain its reputation as a well-connected, accessible, and liveable city must adopt a whole-city approach rather than focusing on isolated solutions. Upgrading existing building stock must account for the liveability of public spaces, ensuring that—beyond building users—visitor and resident experiences are equally enhanced. Three major design issues adversely contribute to these experiences, borne of siloed building design:
1. Extreme heat at ground level: due to concentration of tall buildings and historical proclivity for shiny materials (glass, metal, polished stone), Hong Kong has one of the highest secondary and tertiary reflected glare issues, an issue which has not been effectively mitigated by the introduction of a local design code limitation on external glass reflectance of 20%.
2. Wind tunnelling: fast becoming exacerbated due to increasing severity and strength of winds. Responses to date have seen increases to the thickness and type of materials—particularly glass—to withstand higher wind loads, however this ignores the effects of downwash and wind tunnelling which are exacerbated due to tall buildings and largely “sharp-edged” geometric building forms.
3. Water shedding: vertical shedding in rainstorms from our buildings is a significant component and historically has not largely contributed to extreme flooding events. As we edge closer to more severe rainstorms and greater number rainstorms we must rethink how our buildings are currently design to contribute to the worsening impacts on the ground plane.
Our in-house studies show that external sun-shading and co-joined building awnings on ground level can perform ‘triple-duty’: deflect major solar heat away from buildings and the ground plane, harvest rainwater, and disrupt major wind patterns before the reach the ground plane. External thermal comfort must be prioritised in a city which is so built-up, to mitigate the impact of urban heat island.
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While many studies on Hong Kong’s resilience have been academic in nature, there is a pressing need for industry-led research with practical applications. Applied research must be prioritized to ensure that findings can be effectively translated into actionable solutions. Pilot projects must be shelved for fast deployment. Given the relatively low quality of energy performance in the existing building stock, all improvements to the performance are expected to yield major benefit. Therefore ‘pilot projects’ must be shelved in favour of staged upgrade works.
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Hong Kong currently lacks a robust culture and ecosystem to foster serious practical construction material innovation. Despite the presence of numerous civil engineers and a wealth of expertise, various impediments exist which act to constrain innovation. One of the leading issues appears that in a bid to promote innovation, mandates are enforced around ‘minimum use’ of certain materials or structural systems.
It is critical not to mandate a “single response” to innovations, as the application of solutions is subject to various highly sensitive project-specific factors, including the location and intended use of a building. A specific example in Hong Kong is the mandatory requirement for Modular Integrated Construction (MiC) for government projects. Since the method of construction is highly dependent on building typology (i.e., usage) and location, applying MiC without considering these factors often leads to significantly carbon-intensive buildings.
Establishing an environment that enables the testing and implementation of modern construction materials and technologies, while adhering to stringent safety standards, is crucial. This can be done via a ‘side-along’ regulatory framework to review performance-based designs which do not necessarily comply with prescriptive approach of the building codes. One such successful framework is expert panel reviews, which are currently adopted in Mainland China and India.
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Designers of buildings in Hong Kong rely on a veritable smorgasbord of global engineering codes and standards: American, British, European, Canadian, Australian. This ecosystem, not unlike other jurisdictions in respect of timeliness to adopt new codes and standards, varies in a singular and considerable aspect: engineers working on private developments must submit calculations and drawings for independent government department review. Although the private practitioner is ultimately responsible for their design, the system promotes a quasi-prescriptive design and construction environment due to timeliness of the process construction programme sensitivities and the increasing supply-chain instabilities.
The major structural materials for buildings are concrete, rebar and structural steel. There is a huge potential for carbon saving through using the low carbon material solutions for cement by changing its chemical composition. These innovations focus on cutting the emissions by modifying the chemical reaction processes and much more impactful than what can be achieved by electric furnaces for manufacturing or trying to explore completely different structural materials such as timber. Given that these newer composite materials will not be covered under existing building codes and regulations—developed traditionally decades ago—a different regulatory route for testing and implementation is needed.
The Way Forward is Tough but Tantalising
Hong Kong stands at a critical juncture.
With its unique combination of environmental challenges and opportunities for innovation, the city is well-positioned to lead the way in climate resilience. However, this potential can only be realized through proactive, coordinated efforts that involve all stakeholders from public to private players. Government has a key role to play by improving and providing avenues to encourage practical, industry led innovation. Private sector also has a key role to play to by focusing on meaningful outcomes and long-term gains. A collaborative, forward-thinking approach will not only enhance the city’s resilience but also provide a blueprint for other cities grappling with similar climate challenges.
The stakes are high: failing to act could result in substantial degradation of the urban environment, while taking the initiative could unlock unprecedented investment opportunities and establish Hong Kong as a global leader in innovation, liveability and climate resilience.