OwnerJuly 2015 to presentEl Cerrito

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Friday, March 25, 2011

Building Systems Basics

Commercial and residential buildings account for 39% of total energy consumption in the US. Smart Building has the capacity for greatly increasing building system operating efficiency, reducing greenhouse gas emissions and improving comfort and performance of occupants

Building automation can control 66% of energy in homes and building and since buildings consume 40% of all energy, building automation can control over a quarter of all the energy used in the United States.

1. Background
2. Acronyms/Definitions
3. Business Case
4. Benefits
5. Risks/Issues
6. Success Factors
7. Links

Commercial and residential buildings account for 40% of total energy consumption in the US. Same for CO2 production. HVAC and Lighting account for 60% of commercial building electric energy usage According to Amory Levins, ~75% is wasted.

Smart buildings and green buildings have a lot in common but are not the same thing:
  1. Green Building
    • Sustainable Sites
    • Water Efficiency
    • Energy & Atmposhere
    • Materials and Resources
    • Indoor Environmental Quality
    • Innovation and Design Process

  2. Smart Buildings
    • Data Network
    • VOIP
    • Video Distribution
    • A/V Systems
    • Video Surveilance
    • Access Control
    • HVAC Control
    • Power Management
    • Programmable Lighting Controls
    • Facilities Management
    • Cabling Infrastructure
    • Wireless Systems

  3. Smart and Green
    • Optimize Energy Performance
    • Additonal Commissioning
    • Measurement & Verification
    • Carbon Dioxide(Co2) Monitoring
    • Controlability of Systems
    • Perforamnce Monitoring Systems
    • Innovation in Design

2. Acronyms/Definitions
  1. ACH - Air Changes per Hour - The number of times per hour that the volume of a specific room or building is supplied or removed from that space by mechanical and natural ventilation. Air changes in a confined space are important for a variety of reasons, mainly though, we need fresh air to live. Without sufficient fresh air exchange, moisture is trapped in a room/home/building, molds can feed, and other allergens and excessive dangerous gases (e.g. Carbon monoxide, Carbon Dioxide, urea formaldehyde), can remain in the home. A new focus on energy efficiency is resulting in buildings more sealed from air transfer in and out making fresh air intake very important.
  2. AHU - Air Handling Units - - A device used to condition and circulate air as part of a heating, ventilating, and air-conditioning (HVAC) system. An air handler is usually a large metal box containing a blower, heating or cooling elements, filter racks or chambers, sound attenuators, and dampers. Air handlers usually connect to ductwork that distributes the conditioned air through the building and returns it to the AHU.

    Small air handlers, for local use, are called terminal units, and may only include an air filter, coil, and blower; these simple terminal units are called blower coils or fan coil units. A larger air handler that conditions 100% outside air, and no recirculated air, is known as a makeup air unit (MAU). An air handler designed for outdoor use, typically on roofs, is known as a packaged unit (PU) or rooftop unit (RTU).
  3. Boiler – provides hot water or steam for heating the building or for process needs. Types include, Fire Tube, Water Tube and Modular
  4. Chiller – A machine that removes heat from a liquid via a vapor-compression or absorption refrigeration cycle. This liquid can then be circulated through a heat exchanger to cool air or equipment as required. Provides chilled water for cooling the building or for process needs. Types include: Centrifugal, Screw, Reciprocating and Absorption Moving water around a building is much easier than Freon. Controllable through demand limit.
  5. Coil - Equipment that performs heat transfer when mounted inside an Air Handling unit or ductwork. It is heated or cooled by electrical means or by circulating liquid or steam within it. Air flowing across it is heated or cooled.
  6. Condenser - A a device or unit used to condense a substance from its gaseous to its liquid state, typically by cooling it. In so doing, the latent heat is given up by the substance, and will transfer to the condenser coolant. - A component in the basic refrigeration cycle that ejects or removes heat from the system. The condenser is the hot side of an air conditioner or heat pump. Condensers are heat exchangers, and can transfer heat to air or to an intermediate fluid (such as water or an aqueous solution of ethylene glycol) to carry heat to a distant sink, such as ground (earth sink), a body of water, or air (as with cooling towers).
  7. Cooling Tower - moves heat from the process water that was extracted from the building or process out of the building or process
  8. Air-Side Economizer - Air damper that can save energy in buildings by using cool outside air as a means of cooling the indoor space when the outside air is both sufficiently cool and sufficiently dry. When no additional conditioning of it is needed; this portion of the air-side economizer control scheme is called free cooling. With the appropriate electronic controls, economizers can be used in climates which experience various weather systems. However, because they are generally not tuned, 50% in US cost more than they provide. Good controls, and valves or dampers, as well as maintenance, are needed to ensure proper operation of the air- and water-side economizers.
  9. ESCO - Energy Service Company - A business providing a broad range of comprehensive energy solutions including designs and implementation of energy savings projects, energy conservation, energy infrastructure outsourcing, power generation and energy supply, and risk management. The ESCO performs an in-depth analysis of the property, designs an energy efficient solution, installs the required elements, and maintains the system to ensure energy savings during the payback period. Everything you need to know about ESCO’s is at the National Association of ESCO’s
  10. HVAC – Heating, Ventilating and Air-Conditioning
  11. Packaged System - Air Handling Units that have been packaged for sale based on industry demand. Types include: Roof Top Units, Split Systems, Unit Ventilators and Heat Pumps. Still see VAV systems downstream from packaged systems
  12. Plug Load - Devices that plug into a buildings’ electrical system and include appliances, TVs, VCRs, pop machines, drinking fountains, and office equipment such as fax machines, computers, printers, and copiers. In short, plug loads consist of any electrical
    equipment that is plugged into a wall outlet or electrical plug
  13. Setpoint - the target value that an automatic control system will aim to reach. For example, a boiler control system might have a temperature setpoint, that is a temperature the control system aims to attain.
  14. VAV – Variable Air Volume – Technique for controlling the capacity of a HVAC system. The simplest VAV system incorporates one supply duct that, when in cooling mode, distributes approximately 55 °F supply air. Because the supply air temperature, in this simplest of VAV systems, is constant, the air flow rate must vary to meet the rising and falling heat gains or losses within the thermal zone served. The fan capacity control, especially with modern electronic variable speed drives, reduces the energy consumed by fans which can be a substantial part of the total cooling energy requirements of a building. Dehumidification is greater with VAV systems than it is with constant volume systems which modulate the discharge air temperature to attain part load cooling capacity.

    Control of the system's fan capacity is critical in VAV systems. Without proper and rapid flow rate control, the system's ductwork, or its sealing, can easily be damaged by over-pressurization. Includes reheat coil, fan. Without a remote fan powered box, a centralized 100 HP Air Handler would have to be used.
  15. VAV Box - (aka VAV Terminal Unit) - Sheet metal box + controller
    The zone-level flow control device. It is basically a quality, calibrated air damper with an automatic actuator. The VAV terminal unit is connected to either a local or a central control system
    Advantages of VAV systems:
    • Ability to control temperatures in interior and exterior zones without under or overcooling
    • Capability of taking advantage of varying loads as a result of the sun's diversity
    • Low installed first cost
    • Readily adaptable to night set back and compatibility with energy management systems
    • Economical to operate since the amount of air being moved is only that required to satisfy the load
    • Suitable for partial operation of a building such as overtime or weekend usage of a particular area
  1. VFD - Variable Frequency Drive - A system for controlling the rotational speed of an alternating current (AC) electric motor by controlling the frequency of the electrical power supplied to the motor. Widely used in ventilations systems for large buildings, variable-frequency motors on fans save energy by allowing the volume of air moved to match the system demand. Variable frequency drives are also used on pumps, conveyor and machine tool drives. Big energy savings are often possible when the loads (for example pumps and fans) can be run at a lower speed when the maximum output is not required. Controllable by reducing speed.
3. Business Case
  • Poor building performance is crippling the future of the current industry. Smart Building has the capacity for greatly increasing building system operating efficiency, improving comfort and performance of occupants and reducing greenhouse gas emissions. For example, computer systems embedded during construction will use CO2 sensors to track a building’s occupants at all times, precisely targeting heating and cooling
  • A crash program to improve the energy efficiency of American homes, offices, and factories could slash energy consumption by 23 percent by 2020 and produce $1.2 trillion in savings, according to a report by the McKinsey consulting firm. McKinsey said that taking steps such as better insulating buildings, replacing old appliances, and sealing ducts is the fastest and best way to cut the country’s energy consumption. The firm recommended an investment of $520 billion in energy efficiency programs over the next 10 years, an amount that dwarfs the $10 billion to $15 billion included in the Obama administration’s economic stimulus package.

3. Benefits
  • An efficiency improvement of 50% reduces the size of needed supply by half, or doubles the amount of functionality that a backup supply can support. In this context, rapid improvements in the electrical efficiency of facilities have value far greater than the economic value of its reduced consumption.

5. Risks/Issues
  • Balancing air quality (CO2 levels) with efficiency
  • Simultaneous Heating and Cooling - Occurs frequently in HVAC systems and represents a large opportunity for energy reduction. In systems with primary and terminal level temperature control the lack of coordination between control settings creates waste. Automatic control valves ‘told to close’ don’t always comply. Certain automatic control routines, even with DDC controls, can allow overlap on a transient or continuous basis.
  • Some engineers hate ice storage because it is "less efficient" than stand-alone chillers. In the small picture, this is correct. An ice storage system will use 7% to 8% more kWh than a chiller-only system yet, overall, using ice reduces CO2 emissions and fuel use, not to mention save tons of money. According to the California Energy Commission, during the summer daytime peak, the electric power system is up to 15% less efficient mechanically (peaker plants vs. baseload plants) and thermodynamically (cooling towers and transmission and distribution are less efficient because of high temperatures). In terms of emissions, the on-peak system emits 40 percent more CO2 per megawatt-hour than off-peak. Thus, in spite of consuming more kWh, ice storage is a strong environmental and economic strategy.
  • SEER Deficiencies - SEER is not a reliable predictor of energy performance in California or of demand reduction. PG&E states that the CEC report cited by TURN for the increase in SEER ratings is replete with statements about the inadequacy of SEER ratings in California. For instance, the CEC report states: Current HVAC appliance performance testing is conducted to national standards. Standard ratings for the seasonal energy efficiency ratio (SEER) are conducted at a maximum temperature of 82ยบ Fahrenheit and treat dehumidification as equal to sensible cooling. In the hot dry climates of California, outside air temperatures over 95° Fahrenheit with 35% relative humidity is common. The current standards provide inaccurate assessments of energy requirements during peak periods in California and the Southwest.

6. Success Factors
  • All new residential construction in California will be zero net energy by 2020
  • All new commercial construction in California will be zero net energy by 2030

7. Links
  1. Commercial Buildings Energy Consumption Survey (CBECS) A sample survey of US commercial buildings energy characteristics that is published every 4 years by the Energy Information Administration. The survey includes data on buildings’ energy consumption, energy expenditures, end-use equipment, and energy sources
  2. DOE Zero Energy Buildings Database - This database features profiles of eight zero energy commercial buildings. Each profile contains an overview and information about the process, financing, land use, site, energy use, materials, indoor environment, ratings, and lessons learned
  3. More about commercial buildings research at Berkeley Lab:


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