With respect to the growing requirements on energy performance of buildings, sundry ways how to improve thermal performance of buildings are being searched. One of the ideas is to use some kind of additional “second skin” to create such an environment which would ensure better external boundary conditions and thus improve energy balance of the very house.This paper deals with a case study of a test house which is exposed to the impact of a glasshouse, in which is situated, compared to the situation when no additional skin is used and normal ambient environment affects the house. The aim of the glasshouse is to improve energy performance of the house in winter period. The skin is of such a distance from the house to create extended living space around the house for habitants.Potential contribution of the second skin on the thermal balance of the house is analysed for the climate of the Czech Republic for various scenarios. A simple lumped parameter thermal model (first order model) is used for dynamic simulations with hourly time step. Based on known simplifications of the model, suitability of its application to such kind of issue is also discussed.