ZCB, the first zero carbon building in Hong Kong, aims to showcase the state-of-the-art zero/low carbon building design and technologies in the unique context of Hong Kong. It consists of a 3-storey building (including basement) with a footprint of approximately 1,400 sqm and a landscape area including an urban native woodland.

Key design attributes include:

Four Foundations:

• Educating both the construction industry and public with a view to promoting sustainable construction and low carbon living;
• Experimenting the state-of-the-art design and technologies relevant to the sub-tropical, high-rise / high density context of Hong Kong;
• Evaluating the state-of-the-art technologies with a real-time project dashboard system connecting to the Building Management System and its extensive building environmental performance sensors (over 2,800 sensors); and
• Evolving with the future technology development. Many of the over 80 built-in green features can be further upgraded and expanded.

Three Pillars:

• Carbon Neutral: production of on-site renewable energy and export of surplus energy to offset power consumed from the city grid;
• Energy Positive: generation of on-site renewable energy to provide operation needs as well as offsetting embodied energy used during construction and for major structural materials; and
• Climate Positive: reduction of urban heat island effect with extensive greenery coverage and the use of cool materials.

Three Highlights:

• Waste-to-Energy: first large scale use of biodiesel made of waste cooking oil in Hong Kong through a tri-generation system which harvests the waste heat from the electricity generation for cooling and dehumidification, leading to a high utilization efficiency (>70%) of the source energy;
• First Urban Native Woodland in Hong Kong for promoting biodiversity; and
• BEAM Plus Platinum Rating.

What are the motivations to go “green”?

Within the ambit of the Construction Industry Council Ordinance, one of the functions of the Construction Industry Council (CIC) is to promote good practices in the construction industry in relation to environmental protection, sustainable construction and other areas conducive to improving construction quality. On this basis, CIC developed ZCB in collaboration with the Hong Kong Government. In Hong Kong, buildings account for 90% of the total electricity consumption and 60% of the total greenhouse gas (GHG) emissions. In this connection, buildings are the major contributor to GHG emissions, and are therefore, both a challenge as well as an opportunity for GHG emissions reduction. As such, the construction industry has a significant role to play in GHG emissions reduction. Through this signature project, ZCB not only demonstrates various building designs and features that help to reduce the energy consumption by 45% as compared to the current standard design, but also showcases the use of renewable energy.

What are the major strategies to earn the credits and achieve the BEAM Plus rating?

(I) Energy and Carbon Strategy:

(i) Designing for local context
While there are many zero carbon buildings in relatively cool or mild climates (typically designed to be tightly sealed spaces with little energy exchange with the exterior), there are relatively few examples in the hot and humid sub-tropical climate of Hong Kong. ZCB has the flexibility to switch between a tightly sealed air-conditioned environments, to a highly porous cross-ventilated mode with low thermal storage capacity. The objective is to create a gentle but uniform air-movement throughout the building to counter the often high humidity of Hong Kong.

(ii) Carbon Neutral and Energy Positive
ZCB is connected to the local grid and production of on-site renewable energy offsets the power consumed from the grid on an annual basis. ZCB also goes beyond the traditional definition of a zero carbon building by exporting surplus renewable energy to the local grid to compensate the embodied energy of its construction process and major building materials. The renewable energy is generated on-site from 1050 sqm of photovoltaic panel and a 100kWe Biodiesel tri-generation system.

(iii) Cross-ventilation with High Volume Low Speed Ceiling Fans
This building is designed to address specific environmental challenges in the climatic conditions of Hong Kong. It features an open-plan cross-ventilated layout, when used in conjunction with High-Volume-Low-Speed (HVLS) ceiling fans, promotes a gentle and uniform air-velocity throughout the building that can effectively counter the effects of the often humid weather (free cool for approximately 30 to 40% of the year). A number of high-level windows are centrally controlled by coordinating their operation with the A/C strategy. At the same time, there are a number of low-level windows that can be controlled by the user to tailor the amount of ventilation and air-velocity at the occupant zone.

(iv) Energy efficient A/C
Consisting of under floor air-supply, radiant cooling system and desiccant dehumidification. To deliver the desired room conditions of 26°C, 55% RH, conventional systems overcool the supply air (10 to 14°C) to achieve dehumidification. In this design, the humid fresh-air is pre-treated through a desiccant dehumidification process, hence the air and coil temperatures can be significantly higher, thus putting less load on the chillers.

(v) Energy Cascade
The design also addresses the short-coming of conventional power generation which is inherently inefficient due to the high-rate of heat rejection: only 40% of the source energy is captured. At the ZCB, thermal energy from the combustion of biodiesel is captured in an energy cascade that first utilizes the highest grade heat for electricity generation, then adsorption cooling, and desiccant dehumidification; under such a scheme, 70% of the fuel energy is captured, as compared to 40% in conventional power generation.

(vi) Comprehensive Monitoring
More than 2800 sensors are built into the building to report on every aspect of the building performance. The results are displayed interactively in real-time. This also includes 4 microclimate monitoring stations placed around the site to enhance the understanding of how the building performs and interacts with its surroundings.

(II) Materials Strategy:

ZCB aggressively targeted low energy low waste solutions throughout, with locally sourced (recycled where possible) materials preferred and all transport distances for materials to site logged to enable an understanding of the construction implications.

(III) Site and Native Woodland design:

The building is located optimally in the site to enhance neighbourhood ventilation. This ensures the building is neighbourhood friendly. The location also maximises the collection potential for solar energy. The planted urban native woodland covers 3,000 sqm and consists more than 20% of the total ZCB site area. It includes approximately 220 native trees of over 40 species and a diversity of native shrubs, providing food and shelter to attract native wildlife into the city. The urban woodland creates a high quality ecosystem embedded in a built-up area of the city to benefit both wildlife and people. The species in the urban native woodland are chosen based on four cardinal criteria:
(1) diversity of species composition;
(2) diversity of tree final size and form;
(3) food and shelter for native wildlife; and
(4) ornamental flowers or fruits as far as possible.

The planting pattern is random to emulate the natural woodland, with small trees interspersed amongst the medium and large trees aiming at the formation of a dense tree canopy in due course. Some trees with ornamental traits have been selected to improve visual amenity. The soil mix used in the ZCB native woodland is similar to the soil in the natural woodland in terms of composition and layering. It offers pleasant natural aroma and fresh oxygen and removes gaseous and particulate air pollutants to improve air quality. The site also includes permeable recycled glass pavers and grasscrete to minimise the surface runoff.

(IV) Low Water Consumption Design:

(i) Recycled water
ZCB uses rain, grey and black water systems to reduce the dependency on potable water supply. In a building with a large landscape area, this is essential for the sustainable operation.

(ii) Low water use
ZCB uses water less urinals and other low flow fixtures and fittings to reduce water consumption beyond typical BEAM Plus standards, achieving over 50% reduction compared to the baseline.

(iii) Internal Environment 
A bright and breezy open plan, narrow floor plate design enables the good use of natural ventilation and natural light, which besides from reducing energy consumption improves occupant health and wellbeing. The building is orientated to gain full benefit from the local solar and wind conditions. This is linked to a low pollutant fit out and good quality MEP systems which enable the building to operate with good internal air quality. The building considers different types of occupants and includes a number of enhanced provisions for accessibility and maintenance.

What are the main obstacles during the certification process? And how would you tackle them?

The project was aiming to demonstrate a number of innovative systems. As such the integration of these systems was a challenge. To ensure functionality, a number of advanced simulation techniques were deployed. The building was designed and assessed around a building environmental model – this enabled the whole design team to ask technical performance related questions and receive answers in good time. The model brought together parametric design considerations to predict annual energy savings. This model utilized computational fluid dynamics to predict wind availability across the site and the natural ventilation capacity of the building (Star CCM+), radiance daylight simulations to optimize natural lighting design (Radiance), annual energy simulation to predict consumptions and daily comfort levels (IES Virtual Environment Pro). These modelling processes were brought together to predict the site microclimate, the energy and carbon savings and internal comfort.

Apart from the BEAM Plus rating, what do you consider the key project success? What are the expectation for the future users of the building?

ZCB has won various awards which recognize ZCB’s success in going ‘green’:

• Green Building Award 2012, Grand Award in New Building Category (Hong Kong), Hong Kong Green Building Council;
• Grand Award Winner, Innovation Award of the Year of the Royal Institute of Chartered Surveyors (RICS), Hong Kong Property Awards 2013;
• FutureArc Green Leadership Award 2013, Institutional Architecture, BCI Asia;
• Champion of the Innovation Award for the Engineering Industry (Construction Category) 2012/2013, Hong Kong Institution of Engineers;
• MIPIM Asia Awards, Bronze Award of the Best Innovative Green Building Award 2013, MIPIM Asia;
• International Project Award 2013, Australian Institute of Quantity Surveyors (AIQS);
• Quality Building Award 2014 – Grand Award (New Building, Non-residential), and
• 2013 Hong Kong Awards of Environmental Excellence – Merit Award