This document discusses ventilation requirements and options for dwellings under new Irish building regulations. It outlines the three main ventilation systems allowed: mechanical extract ventilation (MEV), mechanical ventilation with heat recovery (MVHR), and natural ventilation (NV). It notes challenges with NV including inconsistent airflow and studies showing it often under-ventilates. The document compares decentralized and centralized MEV and MVHR systems in terms of costs, noise levels, maintenance needs, and impacts on usable space. It also discusses using wireless sensor networks to monitor indoor air quality parameters like temperature, humidity, and carbon dioxide levels.