Nestled within the hills of the Rift Valley, the Cathedral of the Sacred Heart is Kenya’s second largest Christian place of worship. The new cathedral was built to replace an overflowing church that was unable to support the area’s growing population.

Collaborating with John McAslan + Partners, Triad Architects, EngPlan Consulting Engineers and other consultants, Arup provided a host of services to bring the cathedral’s architectural vision to life, including building physics, geotechnical engineering, and lighting design. 

Since opening its doors in 2015, the cathedral has quickly become one of Kenya’s most celebrated religious buildings. The structure’s distinct and sustainable design can seat up to 1,250 visitors, helping to bring the local community together under one unifying roof. Designed with human experience at its core, the cathedral’s serene and spacious nave helps celebrants to forge stronger connections with their faith – as well as with each other.

A design as green as its surroundings

Every element of the cathedral was designed with sustainability at front of mind. Its various components were made up of a simple palette of natural materials, including timber, clay tiles, granite, stone, and concrete. These materials were sourced and crafted locally, helping to support nearby businesses, while minimising the cathedral’s embodied carbon. This approach also ensured that the cathedral’s finishes and textures aligned with those of its surroundings, helping it to blend seamlessly into its environment.

The building is naturally ventilated, with fully openable side doors allowing natural airflow to be regulated to suit the climate and size of congregation without the need for costly and energy-intensive air conditioning systems. This simple system allows internal temperatures to remain cool and comfortable in every season. 

Additionally, the building’s giant, tilted roof is not only visually striking, but also plays an important role in recycling water. With its enormous surface area, the roof catches large quantities of rainwater. This is used to supply the site’s irrigation system, saving water and costs. 

We analysed local climate datasets to understand the large variations in temperature and light intensity and researched the seismic activity that can occur within the cathedral’s setting. Using this data, we created a resilient design that provides a comfortable place of worship in all conditions, while being able to withstand seismic activity such as earthquakes and tremors.

Collaborating on a local scale 

We worked closely with the local contractor to create a design that the community would treasure for generations to come. The cathedral’s stunning aesthetic played a key role in this. Its structure’s exposed concrete arches create a sense of balance and symmetry that welcomes meditation and inspiration. 

This design required a pristine quality of finish, which was only made possible by our close collaboration with the Kenyan contractor. Working on the site together, our team guided the local contractor to produce the fair-faced concrete structure, while the contractor drew on joinery techniques and craftsmanship to enable the desired quality of finish to be realised. As a result, the cathedral’s arches were cast and struck with clean, sharp edges; creating the instantly recognisable aesthetic that celebrants continue to enjoy to this day.  

Creating an equal experience for all  

Beyond aesthetics, designing a cathedral that offered an equal experience to everyone was one of the project’s defining priorities. This was achieved through the elegant integration of multiple disciplines and design choices. The cathedral’s flat layout seats everyone at the same level and gradient. With no exclusive or separate spaces, this creates a sense of equality that brings together everyone within the cathedral’s walls. The same care and attention towards equality can be seen in the cathedral’s sightline design, with the pews being arranged to enable everyone – regardless of their position in the space – to see the main altar clearly without obstruction. 

However, the advantages of this design came with a set of acoustic challenges, as the cathedral’s shape and hard surfaces create reverberance. Although this enhances the sound of the choir singing, the design also obscures speech clarity and creates echoes. To resolve this, our team implemented an advanced sound system that achieves the dual aims of clarity of speech and fullness of song. This allows celebrants situated in any row to engage with every song, sermon, and prayer. 

The result is a holy space in which everyone can see, hear, and feel the same experience. This creates shared moments of deep spirituality that immerse and inspire all members of the congregation. 

Tranquil daylighting 

Even the cathedral’s lighting was developed with equality in mind. Using a natural daylighting approach, the building’s design distributes light evenly throughout the nave, ensuring that everyone can worship and meditate under the same tranquil conditions.

In response to the cathedral’s equatorial climate, a defusing layer of glass was built into the central rooflight to temper the location’s harsh mid-day sun. This not only improves the comfort of celebrants, but also conceals the passage of time, creating a timeless space of worship that aids contemplation