At its best, architecture provides not just a sound structure for facilitation of activity, but a sense of place—an extension of location and community. This was the overarching goal of John McAslan + Partners when they undertook the Sacred Heart Cathedral of Kericho project in Kericho, Kenya, about 150 miles west of Nairobi.
"The goal was to create an authentically contemporary Catholic Cathedral to house up to 1,500 celebrants that would also be firmly rooted in the local context."
—AIDAN POTTER Design Director, McAlson + Partners, London, UK.
The firm was approached about the project by the congregation’s representative, the Diocese Bishop Emmanuel Okombo, who was familiar with its work in Kenya—a rural school in Malawi. Although based in the United Kingdom, McAslan + Partners designed the project using a team in the UK and executive architects and engineers on the ground in Kericho. The project was led by Aidan Potter, design director with McAslan + Partners, who made regular site visits throughout the duration of the project, as well. Potter’s team collaborated closely with the international multi-disciplinary engineering firm Arup as the project’s structural, acoustic, audio and lighting designer. The two firms met for design workshops in Kenya and London, but Arup was able to work remotely for the majority of the project, according to Caroline Ray, Arup’s project director based in Nairobi.
Lofty Goals, Local Contex
The previous structure in Kericho was a small single-story building unable to accommodate the congregation that had grown from 10 parishes in 1995 to 26 parishes in 2010, when the project began. Therefore, the project’s purpose was certainly a practical one, but it also provided an important opportunity to embrace faith, location and community. “The goal was to create an authentically contemporary Catholic cathedral to house up to 1,500 celebrants that would also be firmly rooted in the local context,” says Potter. Potter and team also wished to make the most of the site, a high point overlooking the Great Rift Valley and visible for some distance. “[We wanted] to establish it as the very heart of the local community,” says Potter. But not in just a physical, visual way. The diocese and design team saw the cathedral’s creation as an opportunity for widespread community participation and commissioned local artists to create indigenous religious iconography and decoration for the finished space. In addition, shares Potter, the team committed to using only locally sourced materials to reduce costs, ground the project in the local context, and benefit the local economy.
Design Methods & Tools
Before any commissioning or material sourcing began, however, the designers researched the local African culture and its intersection with the Catholic liturgy, then took a thematic approach to express the Gothic elements of the building and its structure in a straightforward way, Potter notes. There was also thorough examination of how celebrants would interact with different areas of the building throughout the liturgy and during general circulation. For instance, the nave was widened as it approaches the altar to maximize the number of people able to participate in communion.The design was modeled internally and externally using virtual and physical models; Bentley MicroStation 8 was used to share data with the Kenyan consulting and contracting teams.Concurrently, Arup’s team was using simple hand calculations to evaluate the room’s acoustic performance and used acoustic ray tracing and auralization software to select loudspeakers.Ray shares that her team also researched the Catholic liturgy extensively in relation to light, then used sketches and visualization techniques to develop natural and architectural lighting design concepts. “Lighting simulations using Radiance software and climate-based daylighting techniques were key to understanding the performance of the planned daylighting components and the overall interior appearance and feel of the space,” she says.
Simple, Symbolic Beauty
Rising up from the rolling hills of Kericho, Sacred Heart’s sheer size (14,800 square feet) is striking. Its exterior walls are clad in terrazzo and punctuated by doors made of Kericho-grown Cypress timber. The structure is wrapped on two sides by a plinth built from locally quarried stone and topped with the dramatic, horizontally tapered pitch of the tiled roof.The conic geometry posed a significant challenge to the local contractor, but was accomplished using concrete structural forms and the Kenyan in-situ construction method. “[The forms] were poured and left in-situ and uncovered, which admitted no possibility of mistakes in its casting and formwork,” explains Potter. “[This was] one of the great triumphs of the project.”
The cavernous vaulted interior is essentially one large room that seats 1,500. Multiple points of entry provide ventilation and allow congregants to freely move to the terraces, which cut into the steeply sloped landscape. Although simple, the space is full of symbolism and iconography made from local materials by local artisans. The ceiling’s timber slats, doors and furniture are made from the same humidity-resistant Cypress used on the exterior, while the granite flooring and soapstone used for statues came from the nearby town of Kisii. The chancel flooring and podium are both made of machine-cut Nairobi Blue stone placed by local masons.“This very simple palette of materials contributes to the frugal and unpretentious quality of the building’s aesthetic—that became an important part of its design,” says Potter. An intangible contributor to that aesthetic is natural light. “Light, and particularly natural light, has highly symbolic connotations for the Catholic faith, and an important role in the Catholic liturgy. This was considered carefully in the lighting design for the cathedral,” says Ray.The central axis of the nave is illuminated at a high level by a continuous skylight that casts a diffused yet clear blade of light leading to the altar from the main entrance. “This dramatic ‘Light in the Dark’ symbolizing the luminary teachings of Christ was very much an initiating design theme realized in the final building,” says Potter. Elsewhere in the space, door windows, altar windows and stained glass focus natural light on the sacred symbols of the sanctuary, such as the apse that houses the cross and altar, and the stations of the cross, but were also placed to provide a comfortable level of lighting for occupants.
Balancing Form with AVL Function
Acoustics and audio-wise, the sanctuary’s volume and hard surfaces presented challenges. “The aim was to enable intelligible speech across a range of occupancy levels while maintaining reverb to create a ‘surround sound’ experience to encourage congregational responses,” says Ray.
There was also the need to maintain the clean aesthetic with minimal visible equipment. Accomplishing all of those goals in such a reverberant environment required early planning and collaboration with the architect. “We arrived at a directional ceiling-based system aligned with the timber slats to allow sound to pass easily while keeping the loudspeakers hidden,” says Ray.The team also specified simple, inexpensive loudspeakers from brands readily available in Kenya.Whereas the sanctuary’s vastness created some challenges, it aided in others, such as interior temperature control and the building’s overall sustainability. According to Ray, the roof is a double skin with a ventilated air gap to control heat gain, and the interior space is naturally ventilated, inducing a stack effect to maintain an even and comfortable temperature in spite of the temperature and humidity swings of the local climate. In addition, the team’s commitment to using locally sourced and natural materials reduced transport costs and the carbon footprint of the building. These efforts not only benefited the community during construction, but will continue to benefit it moving forward—which is the noblest goal any project can attain.
[Editor's note: This story was originally published on designerpub.com in November 2016.]
