Modelling the Optimum Heat Store & Biomass Boiler Size

Session 6 Paper 1, CIBSE Technical Symposium, John Moores University, Liverpool
11-12 April 2013

This paper presents a study of biomass boiler and heat store optimisation for a small communal heating scheme. Poor system sizing has been identified by the Carbon Trust as affecting the performance of biomass heating systems, and with the Renewable Heat Incentive encouraging new installations, more are likely to be installed at risk of operating below their full potential. A literature review has highlighted that there is little research directly addressing the subject of optimisation of a heat store for biomass heating systems. This paper studied the problem using a simulation of a communal heating system for a typical 96 flat building. The model was analysed using transient modelling software to establish the heating system size that gave minimum energy consumption and the optimum life cycle cost for the range of options. The model demonstrated that for the systems assessed, the smallest boiler that met the design day average load used the least energy, but when the Renewable Heat Incentive was included, the largest boiler gave the best return on investment. This means that the Incentive will encourage boiler selection that is not the most efficient from an energy perspective.