There is a wide consensus that buildings, as major energy consumers and sources of greenhouse gas emissions must play an important role in mitigating climate change. This has led to increasing concern and greater demand to improve energy effi ciency in buildings. Although, there has been increased efforts to reduce energy consumption from existing building stock; the heritage sector still needs to accelerate its efforts to improve energy effi ciency and reduction in greenhouse gas emissions. Presently, much concentration has been on improving the energy effi ciency of heritage buildings in the domestic sector while, the non-domestic sector has only received little attention. In particular, studies focusing on reuse and adaptation of heritage buildings for public use to achieve more effi cient use of energy are urgently required. The main focus of this paper is the need for research into sustainable reuse of public heritage buildings with reference to maximising energy effi ciency in the process of considering their conversion to other uses. The paper presents part of a broader on-going research with the aim to investigate problems associated with maximising energy effi ciency in reuse and conversion of public heritage buildings. It identifi es the ability of heritage buildings to play a role in global reduction of energy use and CO 2 emission whilst maintaining its unique characteristics. Issues and challenges associated to improving energy effi ciency in heritage building conversion projects were discussed. Holistic approach through identifi cation of various options and innovative techniques for their sustainable reuse were suggested. The paper concluded that in spite of the exemption of listed buildings from energy performance requirements, these buildings can still accommodate some energy effi ciency improvements. However, further studies to identify the most suitable options for long term sustainability is required if the goal to reduce greenhouse gas emissions by 80% by 2050 is to be achieved.

Globally, air-conditioning systems consume over 40% of the total energy consumed by buildings. This accounts for one-third of global greenhouse gas (GHG) emissions, which significantly contribute to climate change. Building designs must take climate into account at all times. This study sought to evaluate passive methods of making residential buildings more energy efficient, hence lowering energy usage. The study concentrated on residential buildings in Abuja, Nigeria. Using a quantitative method, a survey was utilised to collect data from randomly selected respondents. A total of 121 questionnaires were distributed to study participants, and the weighted mean of replies was sorted ordinally from 107 respondents. Although the results indicated that the residential buildings were designed and supervised by architects and engineers, it was surprising that features that could make the buildings more energy efficient were not fully considered in the design because the respondents were unsure of the availability of passive design measures due to their inadequacy. The study emphasises the necessity of considering the micro climatic condition of the building environment, as well as passive design features that could lessen reliance on mechanical means and so use energy efficiently. The paper builds on the findings by arguing for energy-conscious residential building design that takes into account natural dynamics. This might be accomplished by implementing passive design features appropriate for the climatic environment, which could result in a reduction in energy demand for cooling the indoor environment.