A Guide for Architects and Owners:
“Practical Green” Mechanical Engineering from Kohler & Lewis
May 27, 2008

With certain exceptions for very small projects, every Kohler & Lewis project is a “Practical Green” project. Dan Lewis, Joe Kohler, and Roy Swain each have more than a quarter century of environmental and engineering experience. We can work with you on selecting the best mechanical systems, and advise you on the energy impacts of your architectural design issues such as insulation systems, and glazing locations and shading.

We have developed, and continue to develop and refine, innovative yet proven energy conservation and environmental strategies, most of which have only slightly increased construction cost, and all of which have significant environmental benefits or energy savings with good paybacks. These strategies include:

• Electric energy savings through variable speed pumps and fans, using the latest control strategies to monitor the building’s needs and use the minimum energy at any given time.

• Careful ventilation air control through energy recovery heat exchangers and/or continuous monitoring of the “freshness” of the air via carbon dioxide levels, and automatic reduction of the amount of ventilation air to only the amount needed at the moment.

Motor-damper adjusts fresh air to maintain target CO2 levels in room. (Most often, these dampers are hidden from view).	This classroom wing uses occupancy  sensors, and ventilation is shut off completely when a room is unoccupied.

• Wood-fired heating plants, either wood chips for larger buildings and multi-building sites, or wood pellets or cord wood for smaller buildings. We have designed sixteen wood-fired heating systems that are in operation. One more is currently under construction, and one is currently pending.

   
Wood Chip Boiler                                  Wood Chip Boiler Plant

   
Pellet Boiler                                                 Pellet Silo

   
Cord Wood Thermal Storage Boiler            Cord Wood Storage

• A commitment to the ongoing proper operation and maintenance of mechanical systems by specifying Direct Digital Control systems using “web browser” interfaces, so that equipment can be monitored and problems can be automatically detected and reported to service personnel wherever they and their computers are located at the time. Some of these sites are available to the Architect to use as impressive demonstrations.

  
Boiler Plant Screen                                           Air-Handling Unit Screen

• Advanced and optimized use of night temperature setback, by which each individual thermal zone starts up in the morning at the last possible minute, and does not begin ventilation until the start of the scheduled occupancy.

  
Typical Electronic Thermostat                      A Time Schedule DDC Screen

• Innovative new heating/cooling technologies such as variable refrigerant flow (VRF) air source heat pump systems.  These systems, appropriate to small and medium-sized buildings, provide heating and air conditioning using electricity as the only on-site energy source.  (These are similar to ground-coupled heat pump systems, and are just as efficient, but avoid the cost and complexity of the wells or ground loops.)   We have two VRF systems now under construction.

• Efficient gas or oil-fired water heaters (up to 99% efficient) and hydronic boilers (86% efficient), which are capable of burning low-sulfur oil or bio-diesel fuel. One of our projects has burned bio-diesel since 2005.

• District Heating Systems, where several buildings on a campus are heated by a wood fired boiler.  Heat is transferred to the buildings by a network of underground piping.

   
Underground Pre-insulated District Heat Piping (Photos Courtesy of Ray Sebold)

• A concentration on human and environmental health in our plumbing systems, including reduction and elimination of lead and PVC in faucets, solder, valves, and accessories, with a company standard that goes beyond the current federal standard and employs the latest technology and products available in the industry.

   
    Drinking Fountain                                                  DHW Mixing Valve

• Water conservation technologies, including metering public lavatory faucets on every project, dual-flush flush valves, low-flow sink faucets and showerheads, and--where the owner wants to make a more dramatic environmental statement though seldom justified by current economics alone--composting toilets, plumbing drain line heat recovery, graywater recovery, and rainwater recovery for non-potable uses.  Earlier this year, operation began on New Hampshire’s first rainwater toilet flushing system (Kohler & Lewis, mechanical engineers; SVE Associates, civil engineers) at Crotched Mountain Rehabilitation Center in Greenfield, NH.

   
Foam-Flush Composting Toilet                        Rainwater System for Flushing Toilets