There is more than adequate proof that poorly and uninsulated tilt-up concrete construction is a terrible Loop Hole in the Codes that must be remedied.
EXCESSIVE & UNNECESSARY USE OF MATERIALS
One of the main issues with any tilt-up concrete construction, including those with internal insulation, is simply the excessive use of materials where such could have been avoided. These buildings often have thick walls and fairly heavy reinforcing just to support their tall heights, and this large and heavy configuration means that bigger footings with more concrete and reinforcing are required to support the concrete walls' excessive weight. In seismic areas, even larger footing are required to resist the large lateral and overturning forces generated by such heavy walls. As a result, the wall and foundation structure is a self-penalizing series of overstructuring, leading to an excessive use of materials and resources just to erect the heavy walls and to keep them from falling down.
Typically, the roof structures of buildings where tilt up walls are used don't by themselves require such heavy walls for their support. The roofs really only require simple posts, beams, and diagonal bracing for support. If the walls themselves are not already predetermined to be of heavy concrete, then the building's exterior walls can certainly be designed to be built of lighter construction while still providing the necessary support for the roof, if so desired. Eliminating the need for excessively heavy or structured concrete walls then allows more efficient and economical use of materials.
EXCESSIVE EMBODIED CARBON
Another major concern with both insulated and uninsulated tilt-up concrete walls is the excessive embodied carbon that is always present. Both concrete and steel, which are commonly used in these constructions, have a high embodied carbon footprint. The production and transportation of these materials contribute to greenhouse gas emissions and environmental degradation. Even when carbon-free concrete becomes available, the amount of steel required to hold the concrete together is much greater than that which would be required with lighter wall systems.
Furthermore, the construction process of these buildings involves an excessive amount of trucking of materials and workers to the job sites, which leads to the burning of fuel and further creation of greenhouse gases. Similarly, the extra-strong lifting equipment that must be used during concrete wall construction also consumes additional fuel and contributes to a larger embodied carbon footprint.
EXCESSIVE OPERATIONAL CARBON AND GHG EMISSIONS
In terms of operational carbon, uninsulated tilt-up concrete buildings have very little thermal resistance, in essence acting as uniform thermal bridges between the interior and the exterior, leading to more fuel usage and the generation of even more greenhouse gases. Pre-insulated concrete walls, such as those "sandwich panels" with internal insulation cores, offer effective resistance to thermal transmissions, however none of the other concrete disadvantages are mitigated. For most tilt up concrete walls used in commercial and industrial buildings, insulation is often purposefully avoided just to "save construction costs". This lack of insulation is often justified by using loopholes in building codes that allow for less insulation in unconditioned spaces. However, this approach seriously compromises energy efficiency and sustainability.
According to the 2018 International Energy Conservation Code (IECC) Section C402 Building Envelope Requirements, low-energy buildings, which are defined to be either unconditioned spaces or those with a peak design rate of energy usage less than 3.4 Btu/h•ft2 (10.7W/m2) or 1.0 watt per square foot (10.7 W.m2) of floor area, are exempt from the Energy Code's thermal envelope provisions. This exemption can be exploited by developers looking to save costs and result in buildings that may meet the code without proper insulation, but all too often once the Certificate of Occupancy has been issued, these exempt areas become locations where activities occur that require the minimal space conditioning equipment provided to operate much more continuously than planned during certain times of the day and year. Very rarely do these converted spaces receive the additional insulation necessary to properly conserve the energy within the building.
BETTER ALTERNATIVES TO CONCRETE WALLS
To address these issues, a much more sustainable and effective wall solution is the use of lightweight Magnesium Oxide Structural Insulated Panels (MgO SIPs), such as the Simplus Building System™ that also incorporates Passive House™ technologies. These panels provide an insulated enclosure with more than adequate strength to support themselves and the roof loads while significantly reducing both embodied carbon and operational carbon. MgO SIPs also require less time and labor for construction, resulting in a more efficient and cost-effective building process and a better value for the money.
Overall, it is clear that the use of uninsulated tilt-up concrete construction wastes resources, increases costs, and harms the environment. Building Officials and Code Writers should recognize how the use of the exemption in the Energy Code for "low energy buildings" is in fact creating massive amounts of greenhouse gases and must be remedied to combat Climate Change.
A much more reasonable, responsible, faster, less labor-intensive, economical, sustainable, and practical solution is the use of alternative materials and building methods, such as MgO SIPs, especially those systems using Passive House™ technologies. With such we can create buildings that are not only structurally sound but also energy-efficient and environmentally friendly. Given the fact that energy efficiency is critical to combating climate change, it is crucial to reevaluate building codes, eliminate the loopholes that allow for poorly insulated constructions, and to guard against post-construction changes without adequate insulation to ensure a sustainable future for our built environment and its occupants. Responsible architects, engineers, developers, builders, and code officials should stop the use of poorly and uninsulated concrete construction everywhere that energy losses can occur.
