A data processor (4) is disclosed that can be used in a climate control system (1) for controlling a climate in an indoor space (10) or in a design system (20) for designing such a climate control system.The data processor jointly resolves a set of coupled optimization problems of the following form: z Φ k = argmin Z Φ ⁡ ( [ S Φ k ⁢ ⁢ 1 ⁢ ⁢ O ] ⁢ z Φ - Φ ~ k ⁢ ⁢ 1 ) T ⁢ Q Φ k ⁡ ( [ S Φ k ⁢ ⁢ 1 ⁢ ⁢ O ] ⁢ z Φ - Φ ~ k ⁢ ⁢ 1 ) + ( [ O ⁢ ⁢ I ] Z Φ ) T ⁢ R Φ k ⁡ ( [ O ⁢ ⁢ I ] Z Φ ) ( 5 ⁢ a ) subject ⁢ ⁢ to ⁢ [ A Φ k - B Φ k ] ⁢ z Φ - b Φ ′k ⁡ ( Φ k , e Φ k ) = 0 ( 5 ⁢ b ) wherein: z Φ = [ Φ q Φ ] is an augmented state-vector comprising a vector Φ specifying the spatial distribution of a climate related variable with respect to a plurality of spatial cells, and a source term qΦ to be resolved, and wherein z Φ k = [ Φ k + 1 q Φ k ] is the solution found for point in time k+1, {tilde over (Φ)}k+1 being a vector specifying a setpoint specified for said climate related variable at point in time k+1 for at least a part of said plurality of cells, eΦk are boundary conditions relevant for said climate related variable at point in time k, S is a selection matrix, selecting cells for said distribution having a setpoint, O is the zero matrix, I is the identity matrix and Q and R are weighting matrices for tracking and energy consumption, wherein AΦ is a matrix that defines the development of vector Φ as a function of one or more other vectors of climate related variables, wherein BΦ is a matrix that maps the source terms for field Φ to the cell field values affected by those source terms, and wherein the data processor (4) controls the plurality of said actuators in accordance with the source term qΦ.