The building envelope is critical to the performance of a house for various reasons. These are: 

1. Energy Efficiency: The building envelope is responsible for minimizing the exchange of heat between the interior and exterior environments of a house. A well-designed envelope can help to reduce the amount of energy required to heat or cool a home, leading to lower energy bills and carbon footprint. 

2. Comfort: The envelope plays a critical role in maintaining a comfortable indoor temperature and preventing drafts. A poorly designed envelope can result in uneven temperatures, and uncomfortable living spaces. 

3. Durability: The building envelope is responsible for protecting a house from external elements such as rain, sun, and wind. A durable envelope resists wear and tear, prevents water damage or mold growth, and prolongs the lifespan of the building. 

4. Health: The building envelope also prevents the infiltration of harmful gases, pollutants, and allergens. Airtight envelopes with proper ventilation can ensure a healthy indoor environment for the occupants. 

In summary, the building envelope is the foundation of a comfortable, healthy, and energy-efficient home. It provides a barrier to the external environment, regulates temperature, and blocks unwanted noise. A well-designed envelope with high-quality materials and proper installation is critical for the performance, durability, comfort, and health of a house.