TAF-L-W is a fixed linear bar diffuser plenum for underfloor perimeter heating applications. The TAF-L-W's self-contained fin-tube heats the perimeter by utilizing the room air instead of the supply air. By allowing the denser cold air to flow into the TAF-L-W plenum while simultaneously inducing room air into the plenum, the TAF-L-W returns the warmer air to the window or exterior wall through natural convection. This model can help contribute toward achieving LEED Credits.