Lai Chi Wo Eco-Smart Public Toilet: Hong Kong’s first building to achieve Advancing Net Zero

Beyond Hong Kong’s high-rise landscape, approximately three-quarters of its territory remains rural. Within the cluster of villages in Sha Tau Kok region, Lai Chi Wo village stands out as the largest and best-preserved due to various revitalisation efforts (read more in FuturArc 2Q 2023).

With the increasing popularity of Lai Chi Wo, the new Lai Chi Wo Eco Smart Public Toilet (LCWESPT) facility has been constructed to support the growing number of visitors, promote smart and low-carbon architecture, bring a new image to the countryside and better serve the public.

Challenges and solutions

Nestled in the countryside, the project site presented numerous challenges during construction. There were no traffic roads or a public sewerage system; the site is surrounded by sensitive ecology; and it has been zoned as a Conservation Area under Hong Kong’s Outline Zoning Plan, for which a lengthy planning application is required for any excavation work.

Therefore, LCWESPT has been designed as a foundation-free structure, sitting directly on the ground without the need for excavation. The structure is stabilised by counterweights underneath the cubicles. Making use of the level difference in the natural terrain, sewage tanks and pipes are hidden neatly underneath the raised platform.

By using the modular integrated construction (MiC) approach, the cubicles were prefabricated off-site in tailored sizes and transported to be assembled on the project site. This approach helps to minimise construction-related disturbances to the site’s ecology, greatly reduce construction waste, and suit logistical challenges for the remote area, as the materials and tools were only able to be brought in through a small public pier and a narrow track. The consumption of precious natural resources has also been minimised as far as possible by using recycled materials, including pulverised fuel ash (PFA) concrete for the counterweights and yard wood waste.

Vernacular inspiration with modern features

In response to the cultural context and surrounding environment, the facility’s proportions and its southward-sloping roof design was inspired by traditional Hakka architecture. Made of photovoltaic panels with 10 per cent transparency, the roof harvests solar energy while letting in natural daylight to further reduce energy consumption.

Smart sensors are installed to monitor the restroom’s functionality and only use energy as needed, such as: mechanical fans that are activated based on occupancy and air quality; the lighting system that automatically switches on or off based on the amount of natural lighting inside toilet cubicles; and sanitary wares that are touchless-operated.

In view of the facility’s remoteness, the smart sensors also collect usage statistics that would be uploaded to a cloud server for remote monitoring. This allows for advance planning of regular maintenance and timely repair with enhanced efficiency and effectiveness.

To enhance the serviceability of LCWESPT, additional amenities such as a water filling station, seating bench, USB charging outlets and a smart information display are also provided. Ultraviolet light can also be deployed to disinfect and keep dry the interior space. The facility is designed to be inclusive with barrier-free access, as well as having family-friendly and elderly-friendly design features.

Through its environmentally friendly and smart measures, LCWESPT satisfied the Advancing Net Zero (ANZ) carbon emission standards as defined by the World Green Building Council, i.e. 40 per cent reduction of embodied carbon during construction compared to the conventional baseline, and 100 per cent reduction of carbon emissions in energy consumption during the operational stage as offset by the harvest of renewable energy.

PROJECT DATA

Related story:

Architectural Restorations for Remote Countryside Regeneration in Hong Kong

Architectural Restorations for Remote Countryside Regeneration in Hong Kong

Outside of the hyper-dense high-rise compactness of urban Hong Kong, three-quarters of the city’s territory remain relatively rural and undeveloped. There has been more attention to rural revitalisation since the government’s recent launching of countryside conservation policies and funding mechanisms. In 2018, the Countryside Conservation Office (CCO) was established to support innovative conservation of natural and cultural heritages in the remote countryside.1 In Sha Tau Kok, the remote northeastern corner of Hong Kong, a string of lesser-known Hakka settlements is dispersed throughout the hilly coastal terrain. These 300-year-old villages have evolved authentic agro-cultural heritage landscapes, yet most have become deserted […]

Read more stories from FuturArc 2Q 2023: Old is Gold!