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Louvers play a critical role in commercial construction, offering a multitude of benefits. In addition to providing intake and exhaust ventilation, louvers have evolved to become architectural features that seamlessly blend design aesthetics with performance qualities. This article explores the benefits and advantages of incorporating louvers into commercial construction, highlighting their ability to enhance the overall building design while optimizing energy efficiency, indoor comfort, and air ventilation. Moreover, it delves into the significance of incorporating "blank-offs" into the design as well as the importance of rigorous testing to ensure the effectiveness of these systems.

Photo courtesy of Lester Ali

Rose Hill is a new, state-of-the-art residential tower on East 29th Street in Manhattan whose design hearkens back to the classic design of Rockefeller Center. Louvers are installed at the building’s entry level near the occupant entrance, with mechanical components hidden behind custom-cut metal screens.

GETTING TO KNOW LOUVERS

Louvers are horizontal or vertical arrangements of blades or slats that are used to control airflow, water penetration, and even light penetration. By altering the configuration of the blades and varying the free area, louvers achieve certain functions that architects desire for their projects. Installed on the exterior in an opening seamlessly integrated into a building’s facade, louvers can provide a wide range of benefits, including improved airflow and ventilation, privacy, and water protection for sensitive equipment, and offer a creative and unique aesthetic.

There are different types of louvers that architects can specify: non-drainable units; drainable options; storm-resistant products that resist wind-driven rain; extreme weather louvers that can withstand tornados, tropical storms, and hurricanes; acoustical versions that are engineered to minimize noise and sound leaving the building; and blast-resistant louvers that are designed and manufactured to withstand the shockwave from an explosion and not break apart and become a projectile.

The number, size, spacing, and design of the blades provide varying degrees of protection as each blade type has a distinct configuration, allowing for different degrees of air and water to pass through. Generally speaking, the Louver profiles get more complicated as the performance requirements go up. Architects and engineers will need to determine the type of ventilation and water protection they need in order to determine the number, size, and design of the louver panels.

Photo courtesy of Lester Ali

Specifying the louver based on performance criteria is critical to ensure the building not only has ample fresh air, but is protected from the elements and water intrusion.

THE CASE FOR LOUVERS

Louvers have many uses and benefits for engineers and architects. Their primary purpose in commercial buildings is to screen air intakes and vents from unwanted elements and facilitate beneficial air movement in and out of essential equipment, but louvers make buildings energy efficient and comfortable as well. They also offer an opportunity for architects and designers to enhance the visual appeal of their buildings.

To better appreciate how louvers can help improve energy efficiency, sustainability, and health and wellness, it helps to understand their intended function. When combined with other ventilation accessories, louvers help supply additional fresh air to HVAC systems. Outside air is brought into the building, filtered, then picked up by the air handler and cycled through the ductwork. The louvers help push out the hot, stale air, and keep buildings cooler throughout the summer months.

This air-regulating property has an added benefit. Appropriately sized louvers can enhance the energy efficiency of a com-mercial space because areas using outside air ventilation require less reliance on mechanical HVAC systems. The adequate ventilation allows fresh air to circulate throughout the building, creating a more comfortable indoor environment and maintaining optimal temperature and humidity levels throughout the year. The additional ventilation also reduces the likelihood of mold in buildings by reducing the amount of moisture vapor in the circulated air.

Choosing the right louver can also help support sustainable building practices, reduce the carbon footprint of a project and contribute to the overall environmentally responsible goals of a project. When properly incorporated into a design, louvers can qualify for Leadership in Energy and Environmental Design (LEED) credits.

One of the big benefits to louvers is that they help improve indoor air quality by enabling a steady flow of fresh air and exhaust of used air, which reduces the buildup of pollutants, allergens, and odors. Adjustable louvers allow building control systems to manage over airflow, ensuring personalized comfort and improved productivity. By strategically orienting louvers and utilizing advanced materials with high solar reflectance, buildings can minimize energy consumption, resulting in reduced carbon emissions and long-term cost savings.

LOUVER TYPES

In order to select the right louver, an architect must look at each unit’s performance criteria and decide what is needed. Manufacturers likely have their products categorized by depth, free area, pressure drop, wind-driven rain, and extreme-weather defense, including impact rating, giving an indication of the capabilities.

For example, an architect would look at the rain defense to see how successful it is at keeping water from entering through a louver. Rain defense performance is measured by several test methods. Wind-driven rain rejection tests by BSRIA (Building Services Research and Information Association)and AMCA (Air Movement and Control Association) measure a louver's effectiveness under simulated rainfall, air intake, and wind speed. Louvers are organized from the most effective rain defense louver to the least.

Another performance category that architects can check is the louver's Free Area, the minimum area through which air can pass. The free area is determined by calculating the percentage of the total opening that is unobstructed by blades and frame. Such louvers are organized from the highest to the lowest free area. A high percentage of free area allows for more air to enter via a smaller opening, reducing the expenses involved due to less total louvered area required for the same airflow rate. The free areas usually range from 35% to 60% of a louvered opening depending on model and opening size. An important note about free area is that free area and rain defense are inversely correlated, meaning the more free air flow a louver allows, the greater the opportunity for water to move through the louver along with that enhanced airflow. While this is generally true across all louver types, it can be mitigated somewhat with sophisticated blade profiles.

Architects also should specify a louver with a Pressure Drop performance, which is the measurement of the pressure differential from one side of a louver to the opposite side. Pressure drop is used to measure the resistance to airflow across an open louver and is important in the sizing and performance of louvers. It is usually expressed in inches of water at a specified velocity and is always the result of a physical test of units.

An important thing that architects must consider is the depth of a louver or the measurement of the depth of a frame. Depths of louvers vary due to one or a combination of the following criteria: air performance, water protection, sound transmission, installation/site requirements, and aesthetics. When evaluating frame depth, louvers are organized from the widest to the narrowest depth, independent of model type.

The more weather protection a louver system must provide, the more its configuration will have an impact on airflow and acoustics. In order to achieve a successful installation, architects will have to be very clear in their designs and be clear with engineers about the louvers’ “free areas,” keeping in mind that louvers generally perform at about 35% to 60% of free area. As a result, best practices suggest that if an engineer gives you a free area in square footage, you generally need twice as much louvered area to achieve desired performance after installation.

Because louvers are primarily located on the outside of buildings, it’s important that they blend seamlessly with the aesthetics of a building or at least support the project’s overall design. Fortunately, manufacturers produce a wide range of options so architects may specify systems in different sizes, standard and custom widths, different textures, and unique shapes. It’s also possible to intersperse different blade depths within one louver unit or combine performance louvers with various aesthetic scrim elements to blend in perforated sheets, panels, bar grating, mesh, or other design styles.

Louvers typically can be oriented horizontally or vertically and can be finished in numerous colors and textures. Manufacturers offer louvers in a variety of materials such as fiberglass, composite, and wood, but most louvers in commercial applications are made of aluminum although occasionally galvanized steel or stainless steel is available.