Big Buildings / Small Buildings
In most cities there are relatively few big buildings responsible for about 50% of city-wide building sector emissions, and a large number of small buildings responsible for the remaining 50% of emissions.
For equitable and implementable decarbonization pathways, different policy levers and voluntary incentive mechanisms will likely be required for big buildings than for small buildings.
Building intervention points represent key points in the lifespan of a building where there is potential to align and integrate energy upgrades with existing improvement/renovation cycles. Aligning energy upgrade requirements with the appropriate intervention point(s) for each building sub-sector can significantly reduce the cost, disruption, and other burdens incurred by building owners and users during the upgrades.
Big buildings typically have long-term capital improvement cycles and budgets around which energy upgrade requirements can be planned. Date-certain energy upgrade policies allow ample time for alignment with capital improvement cycles, and due to the relatively small number of buildings that would be affected, jurisdictions can implement date-certain energy upgrade policies for big buildings with little to no risk of overtaxing local labor, equipment, and financing resources.
Small buildings typically have more financing options when energy upgrade costs can be wrapped into and financed with other expenditures associated with an intervention point like a mortgage at point-of-sale, a renovation loan at point-of-renovation, or financing for equipment replacement. In addition, aligning energy upgrade requirements for small buildings with a phased intervention point like point-of-sale (as opposed to creating date-certain requirements for small buildings) avoids circumstances in which tens of thousands of buildings try to implement upgrades at the same time which could max-out local labor, equipment, and financing resources. Alignment with a phased intervention point instead ensures an even and steady distribution of upgrades, which has the added benefit of establishing and ensuring the longevity of the energy upgrade job market.
Prescriptive or Performance Requirements?
Prescriptive upgrade requirements are like a recipe: they outline exactly what needs to be done (e.g. use fossil fuel free HVAC equipment). Performance requirements, on the other hand, define the end goal (e.g. zero carbon building operations) but do not outline how that goal should be achieved.
Big building stakeholders often prefer performance-based requirements over prescriptive requirements. Potential upgrade options and ideal upgrade timeframes typically vary much more from one large building to the next than they do within the small building stock, and performance upgrades allow building owners the most flexibility. However some big building owners may prefer the simplicity and (potentially) lower costs of prescriptive requirements; offering both prescriptive and performance pathways for big buildings is typically ideal.
For small buildings, prescriptive energy upgrade requirements eliminate the need to expend time and money on pre-and post-upgrade audits, a requirement for performance-based upgrades, and on any professional expertise required to choose the appropriate energy upgrades. While prescriptive upgrade requirements may limit choice, HVAC systems in smaller buildings tend to be simple and relatively uniform from building to building making most prescriptive upgrade requirements applicable to most small buildings. Prescriptive upgrade requirements, especially when coupled with phased intervention points, also create opportunities to take advantage of economies of scale to lower equipment and labor costs.