Technical
Issue 1
July 2014
BULLETIN Welcome to our very first technical bulletin. This is a new bi-monthly update to provide you with information and topics of interest from across the energy and controls industry. In each issue we’ll aim to provide you with industry updates on technology, product development and legislation. We hope you find this of interest and of course, if there are topics you’d like to see covered in our forthcoming bulletins just let us know
INDUSTRY TOPIC 1 SAVE ENERGY, MONEY AND CO2 WITH AC DRIVES. Wasted money. Pumps and fans consume vast amounts of energy. Often they can be oversized, or running at full power unnecessarily. Fitting an AC drive to your fixed speed pumps and fans allows the motor to run at a speed that matches requirements and enables the end user to capitalise on the energy savings available. What is an AC drive? Otherwise known as a Variable Speed Drive (VSD) or inverter, an AC drive is a device used to control the rotational speed of an AC electric motor by controlling the frequency of the electrical power supplied to the motor. Most conventional motors only run at full speed. However, a motor with a VSD can be operated at a variable rate. This allows the motor to drive a pump or fan at a speed appropriate to system requirements, either stand-alone or automated through technology such as a Building Management System (BMS).
Why use an AC drive? The speed of the motor and energy use are exponentially related. Therefore even a very small reduction in speed can result in a significant energy saving for the end user. Fitting an AC drive to a motor is an attractive cost-saving project for many businesses, as this can provide quick energy saving results within a relatively short payback period. Some interesting facts: “VSDs have the potential to make energy savings and increase profitability in almost every sector of UK business.” “Reducing fan speed not only reduces energy consumption but may also reduce noise and vibration.” “Most fans and pumps are oversized for the duties they perform.” “Using a VSD to slow down a fan or pump motor from 100% to 80% can save as much as 50% on energy use.” You can also download a very useful guide, from the Carbon Trust, which details how an AC drive works and the impact of the technology within HVAC applications: https://www.carbontrust.com/media/13063/ctg070_ variable_speed_drives.pdf How we can help. At ABEC we can offer free AC drive audits and site surveys incorporating energy saving calculations, carbon, kWhrs and payback periods and the full turnkey project delivery to install and commission your AC drives to achieve these outcomes. To find out more get in touch 01684 853 780, enquiries@abec.co.uk
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INDUSTRY TOPIC 2 AUTOMATIC NATURAL VENTILATION – COMPLICATED OR SIMPLE?
SINGLE SIDED DOUBLE OPENING VENTILATION
Energy efficiency is now commonly at the heart of good mechanical services design. Many technologies have entered the race to become the perfect partner for energy efficiency within buildings, such as Combined Heat and Power (CHP), ground and air source heat pumps. Among these Automatic Natural Ventilation stands head and shoulders above these in the technology battle. It offers a simple yet highly effective solution for free cooling and air quality control.
Where multiple ventilation openings are provided at different heights within the façade the ventilation rate can be enhanced with the stack effect. Stack induced flows increase with the vertical separation of the openings and with the inside to outside temperature difference. As well as enhancing the ventilation rate the double opening increases the depth of penetration
of the fresh air into the space, as opposed to single opening ventilation. As a rule of thumb the limiting depth for effective ventilation is about 2/5 times the floor to ceiling height of a building.
CROSS VENTILATION Within modern construction natural ventilation is found in many guises. We see it in actuated windows, motorised louvres and roof turrets to name a few. All of these can be coupled together within different modes of ventilation strategy - such as cross ventilation, stack ventilation and mixed mode mechanical and natural ventilation.
This occurs where there are ventilation openings on both sides of the space. Air flows in one side of the building and out the other through, for example, a window or door. Cross ventilation is usually wind driven but it can also be driven by density differences in an attached vertical chimney. As air moves across the
To provide some understanding of the differences between these varied natural ventilation system designs, we have provided the following summary. It is defined from CIBSE’s Natural Ventilation Guide for nondomestic buildings, AM10: 2005
zone there will be an increase in temperature and a reduction of air quality as the air picks up heat and pollutants from the occupied space. A normal approach to achieving cross ventilation is in opening windows. However other approaches can also be successful. An older example is the ‘wind scoop’, built into the main infrastructure of the building. A roof-mounted ventilator represents a more modern method of this. It uses the pressure difference across a
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segmented ventilation device to drive air down through the segment facing the wind and into the space. The suction this creates through negative pressure draws air back out of the space. Flow rate can be controlled using a damper, with air distribution being achieved via a diffuser module.
AUTOMATIC NATURAL VENTILATION MIXED-MODE VENTILATION Different strategies may be applied to different parts of a building, or at different times. This is the so-called ‘mixed mode’ approach. For example, Changeover Mixed Mode recognises that cooling requirements of any space varies from season to season. An example of this would be to use mechanical ventilation in extreme weather conditions, both hot and cold, but rely on natural ventilation in milder weather. This reduces the problem of cold draughts in winter and allows the use of mechanical night ventilation for precooling in hot summer periods. Each different approach to natural ventilation requires a different level of BMS control, monitoring, interface or integration to achieve a successful natural ventilation control system. A key aspect of this is that it empowers the building occupant to make adjustments to window openings in order to maintain personal comfort, without prejudicing the comfort of others. It means that automatic control strategies need to be carefully integrated with user behaviour.
STACK VENTILATION Stack ventilation is driven by density differences. The approach draws air across the ventilated space and then exhausts the air through a vertical flow path. This means that occupied zones are cross ventilated, in that air enters one side of the space and exits at the opposite site. In order to achieve the required flow distribution without excessively large outlet ventilator sizes, the stack outlet usually needs to be at least half of one storey above the ceiling level of the top floor. This can be achieved with a dedicated chimney or through an atrium. The advantage of atrium ventilation is that air can be drawn from both sides of the building towards a central extract point, effectively doubling the plan width that can be effectively ventilated by natural means.
Some systems, such as roof turrets, come with optional stand-alone controls, which are not required when the technology is being integrated within a site-wide BMS strategy. Window actuators can also cause complications where the typical contractual chain sees these procured as part of the façade package let directly by the main contractor and not generally in sight of the BMS specialist subcontractor of the M&E. So too often by the time the BMS contractor is engaged on the project the actuator selection has been agreed. This removes the opportunity to review and select the best technologies aligned to the overall BMS design. In an ideal situation the actuator selection will be withheld until the BMS contractor is appointed and such detail can be developed through consultation. For an M&E buyer, clarifying which optional items are required is all too often a minefield, presenting possible cost overlap, score gap or warranty issues. A BMS specialist should be able to assist in identifying the boundary points of all packages, to ensure their alignment to provide a combined working technical solution. If not already stipulated by the design consultants, an early review and detailed design of the operability, signals and power requirements between devices (such as the BMS, window actuators and turrets) across all suppliers (façade package, M&E procurement, BMS sub-contractors) is critical to the success of the overall outcome. We work closely with our customers to provide this consultation, ensuring the successful outcome of BMS automated natural ventilation projects. This has multiple benefits, ensuring the end client’s overall building control, energy efficiency and successful contractual delivery of the project.
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TECHNOLOGY & PRODUCT UPDATES # 1 TREND CONTROL SYSTEMS – NEW IQ422 CONTROLLER Small Footprint, Big Capability. The IQ422 is designed for use in a variety of applications. It offers Trend’s smallest footprint for a 12-point universal controller and boasts multi-browser support. The IQ422 is the second variant in Trend’s family of IQ4 main plant controllers and builds on the success of the recently launched IQ41x series. Trend listened to customer requests for a flexible device and has devised a solution that utilises the popular six input/ six output formation, meaning that it can be used in small to mid-sized applications such as primary schools and health centres, as well as larger installations such as multi-tenanted office complexes.
Featuring IQ4 style DIN compatible casework, to fit within electrical enclosures alongside a host of other IQ4 style capabilities, the IQ422 has the power to support the most advanced control applications. These include web supervision using Ethernet and TCP/ IP networking technologies, while XML capability is offered as standard. The IQ422 has open system support and integration features that will benefit IT personnel. A new style web interface facilitates the use of all popular internet browsers including Mozilla, Firefox, Google Chrome, Apple Safari and Microsoft Internet Explorer. It also offers a configurable web server port for enhanced IT acceptance. Data can be accessed via mobile devices such as smartphones and tablets, thanks to a firmware upgrade that detects what type of device the information is being accessed from, ensuring it is presented in the correct format. Graeme Rees, Product Manager at Trend, said: “The IQ422 represents the next generation of our controller technology. It is designed to meet the multi-faceted demands of today’s customers and offers features and benefits that address their requirements for better space utilisation, flexibility and cost effectiveness.
TECHNOLOGY & PRODUCT UPDATES # 2 KAMSTRUP ENERGY AND WATER METERS NOW SUPPORT THE BACNET® PROTOCOL
The manufacturer of heat energy, cooling and water meters, Kamstrup, has developed a BACnet module for its MULTICAL® 601, 602 and 801 heat/ cooling meters and for the MULTICAL® 62 water meter. The new communication module makes it possible to integrate the MULTICAL consumption meters, approved for legal billing, directly into a BACnet based building management system. The new BACnet module adds to the variety of communication options in the MULTICAL meters, which also support LON, M-Bus and N2 besides a number of wireless protocols. The foresight of Kamstrup to provide communication options for its products allows ease of equipment selection when considered for connection into building management systems or AMR system designs, eliminating the need for multiple site networks and gateways, removing unnecessary cost for additional wiring and gateways for different metering network protocols.
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JARGON BUSTING Acronyms and terminology are used throughout the HVAC and energy industry, often leading to misunderstanding. Here we offer some insight to just a few...
AMR – AUTOMATIC METER READING
Most aM&T systems allow the user to set targets for energy use and review current performance against these targets. Many systems automatically produce variation reports and notify users of potential problems by email or text message.
This is the term applied to the automatic reading of consumption data from metering devices such as water, gas, electricity and heat and the transfer of that data to a central database for billing analysis and energy management. A network of meters is established through communication networks (TCPIP, MSTP, RS485, RS232) and protocols (Modbus, M-Bus), to arrive at a central point of data aggregation. This data can then either be used in its raw form by energy managers (CSV files) or collected by intelligent metering software applications like aM&T platforms.
Today many systems are web based and can be extended to cover consumption of other utilities in addition to the traditional electricity and gas use eg: water, fuel, oil, steam. Typically the application of aM&T can lead to savings of around 5%, although often even greater savings can be enjoyed on individual sites. Many users are instantly surprised at the level of avoidable energy waste that they identify.
aM&T – AUTOMATIC MONITORING AND TARGETING This is a software platform and management system that automatically collects energy consumption data and analyses this to ensure energy use is in line with targets set by the user. Energy data can be directly collected from utility providers’ data collection and aggregator services, or direct from site installed AMR systems. aM&T automatically delivers usable energy management information to the person who can make changes.
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We can deliver the turnkey requirements to achieve these outcomes, at site level and through our technical support centre services.
Do you have a current issue? Is there a particular BMS issue you would like us to research and respond to? Is there an acronym you secretly want explained? Do you want to circulate some industry or product news you feel would benefit our readers? Why not drop us a line on bulletin@abec.co.uk
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