To achieve high performance, building systems must use adequate equipment for each application. However, even top-quality equipment performs poorly with incorrect use, and this often occurs when equipment settings are not configured properly. Automatic controls are often recommended by MEP engineers, since they keep the optimal settings for building systems at all times, with no need for manual adjustments.
Building systems can perform their functions more effectively with automatic controls. For example, heating and cooling equipment can control indoor temperature better, providing a more comfortable environment for occupants. Automatic controls also reduce the operating cost of many building systems, achieving synergy with energy efficiency measures. A payback period of less than one year is possible in some cases.
This article will focus on some of the most common applications of automatic controls in buildings, but there are many ways to use them. Building automation systems (BAS) tend to focus on lighting and HVAC, since these two areas often add up over 80% of energy consumption.
Improve your building performance with automatic controls
Automatic Lighting Controls
Lighting fixtures may represent over 20% of energy consumption in commercial buildings, where many work activities require abundant lighting for many hours. The energy consumption of lighting systems can be particularly high if the lamps used are inefficient - incandescent, halogen and metal halide bulbs are some examples. Lighting fixtures also consume more energy if they are left on when not needed, a common mistake when occupants are focused on other tasks.
The best way to control a lighting system changes depending on the application. The most common types of automatic lighting controls are the following:
- Time-based controls simply follow a schedule to activate and deactivate lighting fixtures. These controls are recommended for areas with predictable occupancy.
- Occupancy controls respond to human presence in certain areas. They use sensors that detect occupants with infrared light, ultrasound, or a combination of both.
- Daylight controls respond to natural lighting from the sun. Basic photocells simply activate lamps when they no longer receive sunlight, while more complex systems gradually dim or brighten the lamps according to the available daylight.
Automatic controls achieve synergy with LED lighting, which tolerates continuous switching and dimming. On the other hand, older lamp types suffer a drastic reduction of their service life when they are switched frequently.
The most basic lighting controls simply provide ON/OFF operation, and dimmers are used when brightness control is required. Some LED systems even allow lighting color adjustment and the creation of different “lighting scenes” for indoor spaces.
Automatic Controls for HVAC Systems
HVAC systems account for over 50% of energy consumption in some buildings, and significant savings are possible with automation. Consulting engineers often recommend variable frequency drives (VFD) for air handlers, cooling towers, compressors and hydronic pumps. Smart thermostats are a cost-effective option for smaller installations, and gas-fired boilers can improve their performance with automatic blowdown controls.
Heating and cooling systems are often controlled with manual settings, and they frequently operate at full capacity when only a partial output is needed. In addition to wasting energy, this can cause excessive heating and cooling of indoor spaces, causing discomfort for occupants and potentially health issues. Modern chillers, boilers and heat pumps often come with built-in controls, and no additional equipment is needed in these cases.
Another promising concept is demand-controlled ventilation (DCV), where the fan speed of air handlers is adjusted according to the number of persons in an indoor area. DCV can achieve significant savings in buildings with variable occupancy.
Variable refrigerant flow (VRF) systems are a specific type of HVAC installation that can provide both heating and cooling, controlling the flow of refrigerant according to load. VRF systems have a higher efficiency than conventional heating and cooling equipment, and they save space by using refrigerant lines instead of bulky hydronic pipes or air ducts.
Monitoring, Alarms and Security
Since building automation systems use many types of sensors, they constantly gather valuable data about equipment and associated components. Automatic controls can be configured to send a notification every time they detect an issue that represents danger or requires attention from maintenance personnel.
Alarm systems can integrate with building automation platforms, providing visibility of all zones and their status. Building managers can access this data in real time, and the system can send automatic notifications in response to dangerous conditions.
Automatic Controls for Power Generation and Energy Storage
Buildings with their own generation and storage systems can obtain enhanced benefits from these technologies by adding smart controls. Consider the following example with electricity storage:
- If the building is subject to variable electricity rates, a storage system can be configured to take advantage of low kWh prices, and avoid consumption from the grid when high kWh prices are being applied.
- Energy storage can also be used to reduce consumption peaks, lowering the capacity charges in the power bill.
Energy storage eliminates the main limitation of solar photovoltaic systems and wind turbines, which is their dependence on variable energy inputs. Microturbines fired by natural gas or biomass are also viable in some buildings, providing a controllable power source that makes the building less dependent on the electricity grid.
Automatic controls can enhance all types of building systems, improving their performance while reducing their energy consumption. However, using the right device for each application is very important; the consequences of using the wrong controls range from poor performance to equipment damage and expensive reparations.
Professional MEP engineers can design suitable controls for every building system, specifying the best sensors and communication devices for each application. Automatic controls are often proposed after energy audit, given their energy-saving potential and their short payback period.