When the finishing touches were being put to the Townsend Street housing co-operative in Dublin in recent months, one local wag had a go at naming the new apartment complex. They stuck a piece of paper on the exterior wall and declared it City Farm.

For many, co-ops mean just one thing; groups of enterprising farmers coming together and taking control of the sale and marketing of their produce. But other kinds of co-ops have played a valuable role in the provision of social housing in the state and with the numbers on the local authority housing lists at their highest, it is an increasingly significant one.

Housing co-ops are a form of non-profit housing in which members are the users of the housing services provided through the co-op movement for the benefit of the local community. During the late 1970s and much of the 1980s, 3,000 dwellings were built on the basis of co-operative home ownership schemes - but today, most schemes are rental based. There are 20 such houses or apartment complexes in the Dublin area, and one in Galway, providing 500 homes for those in lower income groups.

Voluntary housing projects such as those run by Focus Ireland or the Society of St Vincent de Paul, which concentrate on providing sheltered housing for vulnerable groups, often act in conjunction with the co-ops. The vast bulk of social housing is still provided by the local authorities who manage a total of 98,000 houses or flats throughout the State.

Brendan Kenny, principal housing officer for Dublin Corporation, is conscious of the importance of such alternatives. "The big difference is that co-ops and voluntary housing associations offer choices to those seeking social housing. It is important for people to have another option. These bodies also provide specific categories of housing for the disabled and the elderly," he said.

Co-operative housing schemes are run in partnership with the local authorities, with the finance for building provided by them through either of two capital assistance schemes. In some cases, the authority has donated the site and the proposed tenants for the homes are drawn from the housing lists of local authorities.

In comparison with other EU countries, the role of non-profit housing associations and co-operatives is somewhat smaller here but this must be judged in the context of the high level of home ownership. As many as 80 per cent of the population own their own homes. Donal McManus, of the Irish Council for Social Housing, has in the past pointed out that local authorities "are by statute the main providers of social housing, whereas in continental Europe, non-profit associations and co-operatives have played a key social housing role for the past 100 years".

According to Bernard Thompson, of the National Association of Building Co-operatives (NABCo), which is directly responsible for the development of the schemes, the homes are occupied by those with "the direst needs".

"But we are not just interested in people becoming tenants, we want people who can become members of a co-op and as such have a stake in where they live," he said.

This ethos is at the heart of the housing co-operative movement and has to some extent shown the way for local authorities, such as Dublin Corporation, which have made well-publicised mistakes in how their estates are run. In contrast, NABCo's schemes are smaller and housing officers have adopted a more hands on approach to their management.

In choosing tenants for the co-ops, NABCo and the relevant local authority go down waiting lists for housing. There are 6,000 names on the Dublin Corporation list at the moment for example, which is an increase of 2,000 in the past two years. Some on the lists may choose not to avail of the scheme but those who do embark on a more involved kind of tenancy.

"Our tenants share responsibility for the management and maintenance of their homes within the co-operative system," said Mr Thompson, adding that even before they move in they are put through a training programme which educates participants as to their expected role within the co-op. The tenants form a management committee, electing their members and attending meetings to vote on issues relating to the administration of the co-op. Having a say in how your complex is managed makes a big difference, said Mr Thompson.

The latest housing co-operative on Townsend Street comprises 16 apartments and the site was donated by the state's largest trade union, SIPTU. Another complex is currently being finished on New Street, near St Patrick's Cathedral, in Dublin.

But the continued challenge for NABCo and other housing associations is to locate sites in the areas where housing is most scarce, or as property prices rise, no longer affordable for those on lower or modest incomes.

What Mr Thompson calls the "erratic availability" of sites has forced NABCo to look at other ways of expansion. "We would be interested in talking to developers who would have an interest in offering social housing on in-fill sites or elsewhere, subject to suitable technical standards and financial arrangements," he said. The development of the Dublin Docklands will also offer opportunities, he hopes, with 20 per cent of the area being earmarked for social housing. "Having a mix of housing is crucial to avoid social segregation," he said.