Deploying low-carbon technologies (LCTs) in buildings, such as photovoltaic (PV) systems and heat pumps (HPs), is necessary to reduce greenhouse gas emissions. Nevertheless, the integration of these LCTs strongly influences the stability of the electricity distribution grids, which thus often require to be reinforced. In this deliverable, we propose a methodology for the quantification of EU low-voltage (LV) grid reinforcement costs following LCT integration. This methodology uses urbanisation data to determine the share of dwellings in urban and rural areas in EU countries. It is also based on a model that evaluates the grid reinforcement cost as a function of the LCT integration scenario for representative rural and urban grids. This model is composed of three sub-models, namely the dwelling, grid and economic models. In addition to presenting each of the developed sub-models, we identified their key parameters. We also collected data from 24 open access grids (i.e. grids of which the specifications are freely accessible online) and 23 scientific articles and reports to determine the parameter values of the grid and economic models for EU countries. The dwelling model, based on occupant behaviour and building properties, produces realistic dwelling load and generation profiles depending on the integrated LCTs. The grid model, based on unbalanced power flow simulations, evaluates the influence of the dwellings’ load/generation profiles and of the reinforcement options on the grid stability. Using the data from open access grids and scientific articles and reports, we were able to define six sets of grid parameter values. These sets represent rural and urban grids of Belgium, Germany and the EU in general. The EU sets can be used for the remaining EU countries, for which sufficient data could not be retrieved. The economic model computes the lifecycle cost associated to a grid reinforcement option. It includes both investment and operating costs of the LV grid. The literature review was used to define one set of economic parameter values that is common to all EU countries. In the last part of the deliverable, we provide an example application that illustrates the methodology by computing the grid reinforcement costs from LCT integration in Belgium.