Development of net-zero energy house (NZEH) optimization has resulted in NZEHs with much lower building costs. However, a viable pathway to cost-effective NZEHs has not yet been made evident. This study uses the Non-domination Sorting Genetic Algorithm II with active Pareto-archiving (aNSGA-II) and Iterated Sequential Search (ISS) algorithms connected with EnergyPlus to perform energy and cost optimizations on seventeen scenarios to determine how NZEHs can become more cost-effective and what is necessary to make them as or more cost-effective than code-built houses. Three house types are optimized in Ottawa, Ontario: a single detached house, an end unit townhouse and a middle unit townhouse. This research finds that a single detached NZEH can be cost-effective if occupant engagement is pursued, if the price of solar photovoltaics decreases to $1.434/W installed, and if the construction costs are similar to that of a large-scale developer.