But pressing on into middle age as the new millennium dawned, the church had begun to show its years in several ways. For one thing, it was leaking energy. The increase of ministries had forced staff into inadequate quarters. Space for the community's social gatherings was limited. Hence the parishioners recent search for an architect to make their creaking edifice more energy-efficient and comfortable for staff and congregation, and to bring it more closely in line with the 'green' thinking now gaining ground in religious groups everywhere.

Their choice fell on Roberto Chiotti, the theologically trained Catholic architect of the Church of St. Gabriel of the Sorrowful Virgin in North York – a recent project widely celebrated for its high environmental sensitivity and the unusual openness of its liturgical space to nature.

St. Gabriel of the Sorrowful Virgin in North York

For Chiotti, the discontents leading to the St. Joan of Arc commission are common in many churches of a certain age.

'A parish will need a survey of their existing building because their roof is leaking, or their boiler is old, or their windows are inadequate,' Chiotti said. 'There is a consciousness around energy conservation, because a lot of parishes have these old buildings that use an incredible amount of energy, and the congregation is shocked every month by the thousands of dollars the parish puts out on energy costs.'

Such concerns, the architect said, are not difficult to address. 'It's easy to fix the heating plant, to double efficiency by putting in a new boiler, or new insulation. You can even imbed photovoltaic cells in stained glass to generate small amounts of electricity for, say, lighting a Reservation chapel.'

(Many more helpful tips, for both individuals and parishes, are available from the Toronto-based Greening Sacred Space Program at www.faith-commongood.net.)

But at St. Joan of Arc, as in other contemporary faith communities considering the overhaul of their facilities, the impulse for change was about more than just energy efficiency.

'They were very intrigued by the idea of reducing their carbon footprint and the output of greenhouse gasses,' Chiotti explained. 'So we came with an idea of the greening of sacred spaces that is part of the consciousness we bring to every project. (The proposed $3.5-million overhaul) is a matter of making (the congregation) more transparent to the outside community. Right now, when you're driving along Bloor Street, you're basically looking at a traditional inwardly focused church that isn't very transparent. We want to create this huge glass greenhouse on the north side of the building on Bloor Street, so that people can see in and see the various activities that are going on, piquing their interest and creating a sense of Catholic presence in the neighbourhood.'

Such forward gestures toward the world beyond the church building is basic to Chiotti's design philosophy. At St. Gabriel's, for example, the architect placed the baptismal font in front of a completely transparent wall, 'with the garden as the backdrop, to make the statement that, as we are baptized into the faith community, we are also accepted into the sacred earth community.' For St. Joan of Arc, Chiotti has proposed an air filtration system composed of plants, intended to become a living symbol of the connection he sees between 'baptism, purifying the air, saving energy.'

Chiotti belongs to a vanguard of Christian architects, environmentalists and intellectuals strongly influenced by the controversial writings and thought of Thomas Berry, an American Passionist priest and proponent of an 'eco-theological' approach to contemporary ethics and religious practice. (The power of this movement among Catholic thinkers is unclear: Two Catholic theologians declined to be interviewed for this article, pleading ignorance of Berry and his writings.)

For Dennis O'Hara – a naturopathic doctor, Catholic theologian and director of the University of Toronto's Elliott Allen Institute for Theology and Ecology – Berry's theology points us in exactly the right directions: away from the restless exploitation and domination of the earth characteristic of Western science and technology, and toward an understanding of God's world as an object of care.

'We've gone wild with notions of dominion (based on the Bible),' O'Hara said. 'We have seen this, in some parts of the West, as justification for doing what we want, what's good for us. We didn't think of other parts of the ecosystem, the bio-system. But we are God's representatives, doing what God would do – keeping chaos at bay, bringing order in creation, doing just what God would do.'

The alternative is further environmental degradation, which, in O'Hara's view, is one result of disobedience to God's plan of cosmic redemption. Because they are graced with scriptural revelation, and threatened (along with the rest of humankind) by climate change and other impending disasters, Catholics have a special responsibility to practise a renewed, creation-based spirituality. One welcome expression of that spirituality, O'Hara said, is St. Gabriel's Church.

'One of the things that's striking about St. Gabriel's is that when the congregation turns to where the Scripture is being read, they turn to a total wall of glass opening on to the garden, which is the rest of revelation. When we look at all the parts of God's creation, we get this sense, a glimpse, of the beauty, the goodness of God.'

But in addition to celebrating nature and God in a steadily evolving universe, Catholics should also promote conversion from the harmful environmental habits of mankind's past.

'As parishes we have to ask: Am I destroying part of God's creation? Who am I to do that?' O'Hara said. 'I am part of a flourishing ecosystem that is going somewhere, maturing, coming to its fulfilment. Am I part of the creation story, allowing creation to come to its fulfilment? If we are decreasing bio-diversity, we are going against that flow. Our church should not have a footprint on the planet that's kicking us in the wrong direction.'