Abstract A Solar Wall Heating (SWH) system was developed to provide low cost space heating in traditional solid stone-walled tenement buildings in Scotland. The SWH system uses the internal solid walls to store the solar heat collected during the day and heat the bedrooms during the night. A physical laboratory model with attached solar hot water system and a computational model of it were developed to investigate the dynamic performance of the system in use and test the cost benefits of iterations of its modes of use. The temperatures throughout the wall structure were measured under the variant solar input of a 24-h cycle. An unsteady state CFD model was developed and validated using the measured data and setup to test a number of key variables of the solar wall heating system in use. These included optimisation control strategies and maximisation strategies for the collection and storage of solar heat under various conditions. This paper presents the modelled results of the solar thermal storage and optimisation system and strategies for internal solid stone walls in a typical Scottish tenement flat in the Scottish climate. In addition the study analysed the solar availability, heating demand and domestic water supply of two typical dwellings based on two reliable methods: (a) a purpose built dynamic thermal model and (b) data collected in previous studies. The study demonstrated that the solar collection of current solar hot water systems can be improved upon so that, even in Scotland, more solar power can be harvested to contribute not only to domestic hot water, but also domestic space heating, particularly in buildings occupied over 24 h with heavy thermal mass. The cost analysis of the system in use suggested a 16 year payback period for such a system for a tenement flat.