Decarbonizing Buildings 3 - ORIGINAL CONTENT

The US Department of Energy (US DOE) has published Decarbonizing the U.S. Economy by 2050: A National Blueprint for the Buildings Sector, which contains a link to the full study.

The first strategic objective in the Blueprint is: Increase building energy efficiency - Reduce onsite energy use intensity in buildings 35% by 2035 and 50% by 2050 vs. 2005.This objective poses two distinct challenges: identifying the ideal characteristics of carbon-free buildings, as the basis for establishing building codes which assure that newly constructed buildings will be and will remain carbon-free; and, identifying the changes which can reasonably be made to existing buildings to achieve the required reductions in on-site energy use intensity.

The logical first focus of these efforts is on the building envelope. For new buildings, all components of the building envelope are candidates for optimization, including slabs, foundations, framing, sheathing, glazing, insulation, interior surface materials, weatherstripping and roofing. Building orientation is also a significant consideration with regard to solar and wind exposure, with particular emphasis on the ability to collect and store solar energy at the site.

The DOE Blueprint assumes that all new buildings would be all-electric. Buildings would be wired for electric appliances and equipment, including heat pump HVAC systems, heat pump water heaters, electric ranges and ovens, electric laundry dryers and EV chargers. Buildings would also be prewired for the installation of solar panels and storage batteries.

The larger challenge is the upgrading of the existing building stock. Ceiling insulation and crawl space insulation improvements are relatively straightforward and inexpensive, as are caulking and weatherstripping. Adding insulation to uninsulated exterior walls is also straightforward and relatively inexpensive. Improving the insulation values of already insulated exterior walls is problematic unless the exterior wall surfaces of the building are also being replaced. Replacing existing windows is expensive and might not be economically justified if the existing windows are double glazed.

Upgrading existing all-electric buildings with forced air HVAC systems should not require any modification to existing appliance and equipment connections. However, buildings with electric baseboard heating systems or steam or hot water radiator systems would require major modifications. Buildings with natural gas or propane appliances and equipment would require installation of electric appliance and equipment connections and might require upgrading of utility electric service and building power panels.

Almost all existing buildings would require installation of connections for EV charging systems. Buildings suitable for the installation of solar collectors would also require installation of the wiring and controls necessary to interface the solar collector system to the building power panels, on-site storage batteries and the utility service.

Achieving on-site emissions reductions would require replacing all natural gas, propane and oil appliances and equipment with electric appliances and equipment. This would likely be accomplished by banning the manufacture and sale of natural gas, propane and oil appliances and equipment and allowing the appliance and equipment replacement cycles to complete the process.

Tripling demand flexibility would likely require that all major appliances and equipment be internet connected to permit remote control of their operation; and, that all buildings be equipped with smart meters to facilitate creation of virtual powerplants. DOE envisions that this would also permit power to be drawn from EV batteries and solar storage batteries if required to support the grid.

As the decarbonization plan comes together, it is likely to include a combination of “carrots and sticks” intended to assure that the plan goals are achieved.