Heating, Ventilating and Air-Conditioning (HVAC) Systems
- Use demand control ventilation for kitchen exhaust hoods and makeup air units.
- Use variable speed drives (VFDs) to control fan speed for ventilation hoods and kitchen makeup air units, instead of two speed on-off fan control.
- When installing kitchen exhaust hoods, select a custom-designed hood that meets the specific exhaust airflow requirements needed by the facility. Selecting a properly sized hood will reduce the fan speed, reducing both energy use and cost.
- Minimize the use of island hoods by locating exhaust hoods near walls for more efficient capture of exhaust.
Although heat recovery can be a great sustainability strategy for office buildings to reduce the heating or cooling load, it is generally not a good idea for restaurants or commercial kitchens. If not maintained and cleaned at a high frequency, the grease and smoke in the exhaust air can clog the heat exchangers.
The largest opportunity to make lighting more sustainable is to replace current lamps with more efficient lamps. For example, within walk-in refrigerators and freezers, replace incandescent lights with low-temperature compact fluorescent lamps (CFL). CFLs give off less heat, reducing the amount of heat the refrigerator needs to reject. CFLs can also be used in the dining environment. However, if the dining environment requires subdued lighting, carefully select dimmable CFLs. Additionally, fluorescent T12 lamps can be replaced with more efficient T8 or T5 lamps. To minimize energy consumption from lighting, all lamps can be connected to a lighting control system with shutdown schedules.
The heat loss or gain from windows can be reduced by applying window film on south- and west-facing windows in the dining environments that get a lot of sun. The window film will help reduce cooling costs, make dining environments more comfortable, and help prevent fading of carpet, chairs and furnishings.
Reducing Demand Charges
A large portion of restaurant energy consumption occurs during peak hours of electricity consumption. Without proactive planning, food service providers may be subject to large monthly demand charges. Two strategies in particular can be used to minimize monthly demand charges:
- Schedule the ice maker to operate during off-peak hours, such as at night. In addition, less heat is rejected into the kitchen, decreasing the kitchen cooling load.
- Use digital demand controllers (DDCs) to control the operation of equipment, such as water eaters, air conditioners, electric space heating units and refrigerating equipment. Using DDCs to interrupt equipment operation for periods of 10 to 30 minutes can help to level the energy consumption load of the building, reducing power demand spikes that can result in large monthly demand charges.
Many small efforts can be made to improve the energy efficiency of refrigeration systems without replacing current appliances. Here are several tips to ensure your systems operate efficiently:
- Make sure that reach-in refrigerators and freezers are not pushed up tightly against the wall. Since refrigerators and freezers reject heat through the coils in the back, space between the wall and the coils is needed to prevent heat build-up. If heat builds up near the coils, the refrigerator or freezer will need to work harder, consuming more energy
- Periodically clean the coil fins as part of the preventive maintenance routine for refrigerators and freezers. Over time dust builds up on the coils, reducing the efficiency. Dust can contribute to equipment failure or more frequent maintenance service calls.
- Decrease energy consumption used for defrost cycles by setting refrigerator defrost cycles to meet the needs of the operation. In most cases, four 15-minute defrost cycles are sufficient. Adjusting the defrost cycle can result in a significant energy and cost savings.
- A low-cost upgrade for walk-in refrigerators is replacing strip curtains. Strip curtains alone can reduce outside air infiltration by 75%. Utility rebates are often available to cover a large portion of the capital cost. With the rebate, the payback can be less than one year.
Energy is used for cooking, food preparation, cleaning and dishwashing.
Energy is also used for refrigeration, ventilation and many other applications. The type, model, age and how the appliance is used greatly impact energy consumption. Efficient use of energy can reduce operation costs while having a positive environmental impact.
Using reusable dishes and flatware, combined with energy- and water-efficient dishwashers and environmentally preferable detergents is one option to reduce solid waste. When disposable flatware is required, compostable flatware is an alternate environmentally preferable option. However, compostable flatware must be directed to a commercial composting facility, as it will not degrade within a landfill environment. When making decisions about disposable flatware and dishware, be sure to consider products made from renewable materials, post-consumer content and products that are compostable.
Measuring the Environmental Impact
Determining the environmental impact of a food service operation can reduce operational costs and improve environmental, financial and operational efficiencies. Like other sustainability initiatives, it is best to start by defining the goals of the effort and start with a small pilot project. The first step to measure the environmental impact of a food service operation is to determine what data should be collected, considering what environmental impacts are to be quantified. The data can include, but is not limited to, procurement practices, water consumption, electricity consumption, chilled water consumption, steam usage, volume or weight of compostable materials, recyclable materials and trash. Collecting water and energy consumption data is often the easiest place to start since most of this information is contained within utility invoices. Waste stream and supply chain data are often the most difficult to gather since this information is often scattered.
When collecting energy consumption data, it is important to differentiate between direct and indirect energy sources, and renewable or non-renewable sources, as each type of energy has a different emission factor. Differentiating between renewable or non-renewable energy sources is relevant when a facility has solar panels, wind turbines or purchasing agreements with the utility to provide a certain percentage of electricity from renewable energy sources. A direct energy source is one that is used directly to generate energy that can be used at the food service facility. An indirect energy source requires an intermediate process in order for the energy source to be used. For example, steam is an indirect energy source, produced from burning coal.
Procurement data includes the amount of sustainable products purchased, such as sustainable seafood, fair-trade coffee, environmentally preferable serviceware and products containing recycled content. Volume and dollars (or other monetary units) are common units of measure for supply chain data because they are readily available from invoices and other tracking systems.
In general, invoices are a good starting point for collecting data on procured products, water, energy and waste. When requesting invoices from others, it is important to explain why the data is being collected and how it will be used. This will help the people providing the invoices understand the value of the efforts and take ownership in the project. When invoices are not available, estimates and measurements can be used. If estimating data, document the methodology or conversion factors used. For example, electricity consumption data could be divided equally among all buildings or calculated based upon the occupied building area. Take caution, however, in that location-specific usage patterns and building types can have a large impact on electricity consumption.
More simply put, 25% of the building area may not actually translate to 25% of the energy used. Similarly, waste generation data can be converted from volume to weight using standard conversion factors. In all cases, it is important to document the source of the data, as estimated figures may vary greatly from an actual reading – ultimately impacting the accuracy of the data. Commercially available software systems can support effective data collection and analysis. Several software vendors offer solutions that are specifically designed to collect and manage resource consumption data, calculate greenhouse gas emissions and generate reports. For small calculation efforts, spread sheets can also be used.
Normalizing data enables an evaluation of efficiency measures, allowing comparisons from month-to-month and year-to-year at specific locations. Data can be normalized using several different units: number of guests, building area or revenue generated. After two to three years of data is collected, a benchmark for the facility can be established, which helps with decision-making. To start making decisions using the data, look for direct comparisons that allow conclusions to be drawn about practices within the organization.
For example, compare the tipping fees for land-filled trash and recycling. If tipping fees for trash can be reduced, both environmental and economic benefits result.