Design Considerations Balance Sustainability, Safety Needs
The following article is based on an excerpt from “Security Design for Sustainable Buildings and Campuses,” a book released this year by security consulting firm Applied Risk Management. It outlines several areas where sustainability and security collide, and solutions for both areas of facility management.
Outdoor Lighting
With respect to security, the more outdoor lighting a building has, the better. Lighting is considered a deterrent to crime because criminals prefer to carry out their activities under the cover of darkness.
From a security standpoint, the optimal lighting level is when shadows and blind spots are eliminated. Security also calls for enough outdoor light to support camera surveillance. Lighting is particularly critical in parking lots, which are the leading locations where crimes are likely to lead to a lawsuit for facility owners.
Perhaps the greatest sustainability concern regarding outdoor lighting is the issue of light pollution, which occurs when a building’s outdoor lighting disrupts the environment surrounding the building disturbing nearby people or animals. Energy conservation is also a major sustainability issue forcing building designers to balance energy and sustainability concerns.
Traditionally, outdoor lighting output and coverage are maintained at a fixed level based upon worst-case scenario ambient-lighting conditions. However, it may not be necessary for security purposes to provide constant outdoor lighting for the entire outside area surrounding the building.
One way to balance security with sustainability is to strategically install outdoor lighting only in those locations that require it. Depending upon the unique characteristics of the property, it might be more practical to only provide outdoor lighting in particular locations, such as dedicated after-hours parking areas and common pathways defined by landscaping and signage.
Advancements in lighting technology provide another outdoor lighting solution. Rather than using lights that provide a constant level of illumination, designers can now use variable intensity lighting systems, such as light emitting diode lights that can be adjusted according to the amount of ambient light in order to achieve the level of lighting selected by the user via a sensor-control system. Light sensors, such as photoelectric cells, can also be used to control the amount of illumination based upon ambient lighting.
Cutting-edge innovations in video analytics can provide a new form of intelligent lighting control that maximizes and integrates security and sustainability. This technology is currently used to detect and track the movement of people and other objects of interest.
Indoor Lighting
Safety codes, which vary from state to state, require a minimum amount of light to be maintained indoors at all times. While code requirements may sometimes conflict, they all call for about 1 footcandle of illumination (i.e., about enough light for an average person to read newspaper print) measured at floor level at all points along an emergency egress pathway.
With respect to natural lighting, guidelines call for minimizing fenestration (the percentage of openings versus solid walls) in order to provide blast protection and ballistic protection.
However, sustainability initiatives call for daylighting through the use of as many windows as possible. The use of natural light reduces, and can even eliminate, the costs of electric lighting and conserves energy.
The use of intelligent lighting controls with occupancy sensing can integrate interior lighting safety and sustainability. With this type of control, indoor lights are off unless the light sensors detect motion indicating that the room is occupied.
Another type of control is scheduling, which allows the building user to specifies when the lights should be off and on according to a pre-set schedule. Lighting can also be controlled according to how much daylight is in the room.
A cutting-edge innovation involving the integration of indoor lighting with access control systems can improve sustainability and security. Through such integration, indoor lighting can be used intelligently according to who is in the building. For example, when the access control system senses that an employee of the building is entering, it may light that employee’s work space to full lighting level.
However, when it senses that security personnel are entering the building or area, such as during a routine patrol, the lighting may remain at the minimal level. Keeping the lights at a low level is ideal for the security guard, who would not want his/her presence announced to an intruder through light activation.
Exterior Envelope
The greatest security concern regarding a building’s structure is its ability to withstand a blast from an explosion. The primary structural concern is to prevent progressive collapse of the building. Beyond this, the blast that enters the building can cause enormous destruction and injuries even if the building remains standing.
These concerns are addressed first and foremost by providing adequate stand-off distances with a defined protective perimeter around a building that limits the approach of a postulated blast threat, structural design, exterior envelope design or a combination of these elements.
Sustainability calls for energy conservation through the use of heat reservoirs in cooler climates, and through barriers that provide heat deflection in warm climates. In the former case, walls or other structures built around the perimeter of a building can be used to absorb heat during the day, insulating the building and providing heat during the night. In the latter case, barriers around the building can provide shading from the sun, reducing the amount of energy consumed in cooling the building from within.
In addition, sustainability calls for minimal disruption to the environment. A building’s structure should blend in with its environment wherever possible.
In many ways, the concerns with security and sustainability regarding the exterior envelope are aligned with each other. Both call for an energy reflecting and/or absorbing exterior envelope in order to conserve energy and provide blast mitigation.
However, security and sustainability are at odds with each other with respect to the heat-island effect.
For example, sustainability would be maximized by placing a building’s parking garage underneath the building, rather than creating a heat island in the form of an outdoor parking lot. Security, however, would view the placement of a parking garage beneath a building as a serious threat, as a truck bomb parked beneath the building could do far more damage than one located outside the building.
Many solutions can be found that will maximize both security and sustainability. For instance, thermal mass walls, also known as Trombe walls, can be used to provide a building with both blast mitigation and heat insulation.
Trombe walls reduce energy consumption while also acting as a barrier around the building and providing blast protection.
Landscaping
Landscaping can best be used to increase security through the use of Crime Prevention Through Environmental Design techniques. CPTED uses natural access control, natural surveillance and territoriality and boundary definition to reduce the opportunities for crime.
Natural vegetation and other natural elements of the landscape, as well as signage and lighting, can be used to direct foot traffic. Blast mitigation through the use of landscaping, such as trees, can be used to keep vehicles away buildings. Trees used for this purpose are generally located in concrete planters or other engineered landscape features.
Landscaping can be used to reduce the heat-island effect and conserve energy. For example, trees can be used to provide natural shading of buildings in warm climates, thereby reducing the amount of energy needed to keep the building cool.
Security and sustainability can be achieved through the use of variable grading, which is when a building’s structure is designed to accommodate the natural contours of the land, rather than.
By erecting a building within the natural landscape, the environment preserved and natural hills can provide blast mitigation and prevent vehicles from running into the building.
Rainwater reservoirs used for water conservation ponds can also provide blast mitigation, essentially acting as moats protecting the perimeter of a building.
Green vegetative walls or water walls, partially buried structures and buildings with roof gardens are also aligned with both security and sustainability goals. Furthermore, vegetative or water walls can disguise unattractive blast walls without windows.
High-canopy trees can be used to shade buildings without blocking the sightlines of security cameras. A small grove provides an ideal option to protect a building’s secure perimeter.
The use of native plants with thorns can deter pedestrian intrusions. Vegetation solutions can also be integrated with seating, statues, and retaining walls to create a park-like setting.
To meet sustainable and security goals, parking lots and parking garages should be eliminated or minimized to encourage the use of public transit. Bike paths adjacent to the property provide additional setback, and bike racks provide an additional obstacle that must be traversed in order for a vehicle to impact a building.
Placing public lobbies within a separate glass pavilion outside the building can permit both nature and light to enter while providing a more efficient way of protecting interior spaces against threats.