Abstract: Flat glass annealing lehr equipped with controlled heating and cooling means, includes pre-annealing, annealing, and post-annealing zones with heat exchange by radiation, the said zones being equipped respectively with groups of cooling-air heat exchangers situated above and/or beneath the glass ribbon. A single cooling-air intake manifold is included for groups of exchangers in the pre-annealing and annealing zones, which manifold is situated where the zones meet. A single cooling-air intake manifold for second groups of exchanges in the annealing and post-annealing zones, which manifold is situated where said zones meet.