Home Insulation

The building envelope of a residential home defines the outermost shell that protects the conditioned indoors from heat, cold, moisture, noise and light from the outside. The main components are walls, roofs, windows, doors, and foundations. The excellent thermal performance of external walls is of particular importance to maintaining a comfortable indoor environment at low energy consumption (Ibrahim et al., 2014). An improved thermal wall system reduces heat losses, operating cost, and reliance on HVAC systems. Several methods can be used for improving the thermal performances of wall assemblies that include (Kosny et al. 2014):

• 

  Fig. 1 Heat loss through uninsulated walls

  Using thicker and wider insulation space in the wall cavity 

• Increasing thermal resistance of insulation materials 
• Using insulating sheathing 
• Controlling and reducing thermal bridges 
• Using airtight construction methods 

Two main problems associated with the poor thermal performance of wall assemblies are air leakage and inadequate insulation. Studies have shown that heat losses through poorly insulated walls can be as high as 35% compared to a code compliance wall assembly (Fig 1). Hence, higher levels of airtightness and wall insulation are required by modern building codes (Boudreaux et al., 2018). Similarly, the BC Energy Step Code (BC-ESC) introduced in 2017 and applicable to new residential buildings requires an even higher level of insulation and airtightness. Increased insulation levels in wall assemblies of residential buildings can help in meeting energy performance targets defined by the BC-ESC. 

What was tested? 

In the Wilden Living Lab (WLL), Home of Today (HOD) and Home of Tomorrow (HOM) are built with wall assemblies with the effective thermal resistance (R) of 17.16 K·m2/W and 21.46 K·m2/W. The heat recovery ventilators are used to enhance the energy performance of both houses and to comply with the BC Standard building code 2015. The details of the exterior wall assemblies for the two homes are provided in Table 1. In this article, we employ energy data collected through the installed sensors in the two homes to develop calibrated energy models. The calibrated models were normalized to separate the energy and costs benefits associated with individual components of the WLL homes. The results of wall assemblies of the two homes are further tested for different wall assemblies comprised of multiple insulation types and thicknesses with different airtightness. The total combinations generate six (6) different scenarios, as shown in Table 2. The results of these scenarios can help in making decisions when selecting exterior wall assembly in Kelowna.