Five Key Design Concepts for the Sitka Renovations
Heating Load Reduction. Through investing in the building envelope and heat recovery ventilation, the heating load was reduced by approximately 50% for these three buildings. This was done with high performance glazing, extra insulation in the walls and roof and heat recovery ventilation for tempering all the ventilation air. This shifts money from the mechanical system to the building envelope since the mechanical system can be significantly smaller. These envelope investments last 30 to 50 years or more and can be most cost-effectively implemented during major renovations.
Dedicated Outdoor Air System (DOAS). The heat recovery ventilators were configured as DOAS with the ventilation ducted separately from the heating and cooling systems. This design approach significantly reduces duct sizing and fan energy since only the ventilation fans need to run for most hours of the day. Typical designs coupling ventilation with heating and cooling equipment must rely on the much larger HVAC fans to run continuously to deliver the ventilation air.
Zonal Heating Systems. With ventilation separated from the heating and cooling delivery, systems were designed to allow for maximum zoning control to turn off equipment in areas where and when it is not needed instead of large central fan systems, which must run during all occupied hours.
Right-Sized Equipment. Careful sizing calculations instead of “rules of thumb” allow for smaller systems with cost and energy savings and better comfort and acoustics.
Decarbonization. Elimination of fossil fuels through use of biomass or heat pump technology for space heating and domestic water heating dramatically reduces carbon emissions without adding electric resistance, which could over-tax the electrical grid.