Façade retrofits and window replacements: a wicked problem
There is a huge opportunity to improve existing building envelopes. According to the U.S. Department of Energy (DOE), 40% of commercial and multi-family buildings, approximately 2.4 million structures, have single-pane, non-thermally broken windows. There are many energy-guzzling, uncomfortable buildings where people work and live. Yet, the façade retrofit annual rate is less than 1%, much lower than needed to meet building decarbonization needs.
The report on market barriers by the Façade Tectonics Institute (FTI) explains why retrofitting buildings with high-performance façades is even more complicated than implementing high-performance façades in new buildings. Not only do retrofit projects face the same seven barriers as new construction, but they also face many others.
Façade retrofits do not happen because they are high risk, complex, disruptive and expensive. The most impactful root causes are summarized below.
You Touch it–You Own it
In many jurisdictions, if the façade’s structure is altered, the project team must justify that the structure will remain functional. In some cases, the façade must be upgraded to the current structural or seismic code. For example, if the frame is touched in any way in California, it must be upgraded for seismic compliance. This typically means reconstructing the building. In some jurisdictions, the line for structural assessment is when more than 5% of the façade is altered.
Hardening requirements, such as blast resistance, can also be required for government and certain private buildings, further increasing the cost of “touching” the façade.
These structural, seismic and hardening upgrade requirements are often enough to prevent owners from taking on the liability and cost of extensive façade replacements.
Unknown Existing Conditions
A major contributor to the risk profile of retrofits is the inability to know the façade conditions—and therefore the scope and cost—before starting the project. When original documentation or as-built drawings are no longer available, as they are typically not, the architect and/or façade consultant must design the retrofit based on onsite observations alone.
The state of the façade and its anchoring often cannot be known in advance. When the project team does not know the original design load, they typically will remove a few existing anchors to assess their depth and condition. If the anchors are insufficiently long, new, longer anchors will need to be installed, which may run into existing rebar within the concrete structure. All of this can substantially increase costs and impact the building’s structure.
In short, the owner may need to spend $1 million to assess whether an upgrade is even possible on a $10 million upgrade, with a high risk of finding that the upgrade is not viable.
The unpredictable availability of skilled labor adds additional challenges. Situations often occur when the onsite team encounters unexpected onsite façade conditions and is not sufficiently experienced to manage them.
Architects assert that requiring owners to retain shop drawings for their buildings would go a long way to supporting retrofits.
Set Back Issues
Existing façades often butt up against or bleed over the setback—the minimum distance from the property boundary according to zoning requirements. As a result, it is frequently not possible to make walls thicker or add sunshades without special dispensation from the local jurisdiction.
Tenancy Complexity
Envelope retrofits are disruptive and may cause tenants to move from the building or owners to wait for staggered leases to conclude before upgrading. This causes many months of lost rental income. When tenants remain in place, this can limit the types of façade retrofits installed. Additional costs are also incurred because of the complex logistics of minimizing tenant disruption from noise, air quality and thermal comfort. In urban settings, streets may have to be closed to allow crane access, adding more costs.
Window and Façade Replacements Don’t Pay Back in Sufficient Time
Because of the high costs of retrofitting high-performance fenestration systems in existing buildings, payback periods for window retrofits can often exceed 20 years in the U.S. Payback periods in other developed countries, such as in much of Europe, are shorter because of their higher energy costs and availability of lower-cost, high-performance fenestration.
Improved occupant comfort, fewer mold-related problems due to condensation, thermal resilience and other benefits provided by fenestration retrofits are more challenging to quantify. Such benefits are likely to offer more financial payback beyond energy savings alone because of the positive impacts on human health, wellness and productivity. This is because knowledge workers’ salaries are approximately 100 times higher than energy costs in a building. As a result, a relatively small 1% increase in worker productivity is worth more than a 10% decrease in energy costs.
The only benefits typically considered for commercial real estate owners are energy efficiency and higher lease rates, since they are more easily estimated and validated. For owner-occupiers, occupant comfort and thermal resilience may factor into replacement decisions.
An increasing number of jurisdictions are adopting building performance standards (BPS). These require buildings to meet a defined annual energy use intensity or pay a fine. BPS is changing the payback equation and is providing an impetus to improve building efficiency in adopting jurisdictions. If the jurisdiction’s annual penalty for not achieving the target energy efficiency is large enough, window replacement and/or façade retrofit may be financially viable. It is unclear if New York City’s Local Law 97’s penalties are sufficiently high to drive larger façade retrofits or if owners will pay the fines.
It does not help that curtainwall systems are not designed for easy upgrades and maintenance. To quote FTI’s ambassador of innovation and collaboration, Mic Patterson, “Curtainwall systems are good, until they are not.” Seals and gaskets are inaccessible in a unitized curtainwall. The curtainwall must be torn down and replaced when it fails, even though the aluminum extrusions are still serviceable. Longer curtainwall lifetimes could be achieved if they were designed with readily accessible sealants and gaskets for upgrade and replacement.
Consequences
There are three major consequences of these significant barriers to façade and fenestration retrofit:
- Poor performance is maintained: Due to the unknowns, the liability is too high to take on a façade retrofit, so no action is taken to improve the façade.
- Façade is the last upgrade: Upgrades to lighting and HVAC systems are done first by building owners because they are much less expensive than a façade retrofit or window replacement.
- Incentive to rebuild: Sometimes, it can be cheaper and/or lower risk to tear down and rebuild rather than renovate. However, this is not desirable because of the additional embodied carbon emissions. Therefore, jurisdictions need to provide incentives to retrofit and create more barriers to demolition.
Solutions to Drive Façade and Fenestration Retrofits
FTI proposed six different solutions for overcoming the barriers to façade retrofit:
- Drive the adoption of BPS across more jurisdictions with penalties for non-compliance that are sufficient to drive retrofit investment.
- Increase the awareness and deployment of secondary glazing systems. These systems can be installed with minimal impact on the existing façade, and although they do not have quite the same thermal performance as a complete retrofit, their reduced cost, complexity and disruption may deliver more energy savings because of more widespread adoption.
- An embodied carbon assessment is required as part of the plan approval by the code official to disincentivize demolition and rebuild, as has been implemented by the City of London.
- Provide financial incentives for façade surveys to reduce financial risk in assessing the potential for retrofit.
- Provide financial incentives for façade retrofits to change the cost-effectiveness equation.
- Fund research, development and deployment for curtainwall system designs with an extended lifetime.
