This article connects the literatures of policy evaluation, policy mixes and sustainability transition. It utilises client-oriented evaluation to examine national policies in Finland from the perspective of low-carbon buildings transition. In Finland, energy efficiency has traditionally received less focus in energy and climate policy strategies compared to renewable energy. Since 2007, energy efficiency policies addressing buildings gained force. Sixteen new policy instruments were implemented during 2007–2014 and several revisions were made to the building code energy efficiency requirements. To what extent these changes contribute to ‘creative destruction’ in the policy domain is uncertain. Therefore, we conduct a client-oriented evaluation of the policy mix from the perspective of a boundary actor—integrated energy service companies—to analyse its potential for facilitating zero-carbon transition. The findings show a divergence of opinions regarding the policy mix’s disruptive influence. Where potentially disruptive policy instruments can be found, their impact is reduced due to incoherence in policy implementation processes. The usability of client-oriented evaluation for policy mix analysis is found limited on its own but useful in complementing top-down policy evaluations. We also propose an additional function to the creative destruction policy mix: ‘changes in organisational and institutional practices’, linking to the coherence of policy mixes.