Does the application of Green Technologies always result in increased HVAC capital costs?

Variable Refrigerant Flow Systems – An Independent Case Study The continuous drive towards designing buildings and systems that significantly reduce our impact on the environment is pushing the innovation envelop within the HVAC industry. Does the application of ‘Green Technologies’ always result in increased HVAC system capital costs? Mitsubishi Electric is widely recognized as world leaders in the design and application of variable refrigerant flow systems for over thirty years. Even though such HVAC technology has been considered mainstream in both Asia and Europe for over twenty years variable refrigerant flow systems (VRF) are still considered by many as an emerging technology in both the United States and Canadian markets. Given this landscape conflicting or extremely limited market based information is currently available in Canada with regards to how the first costs of variable refrigerant flow systems compare with what is considered the more traditional four pipe chilled and hot water HVAC approach.   Variable Refrigerant Flow – The Concept Variable Refrigerant Flow systems control the amount of refrigerant flowing to individual indoor units. This allows for the use of multiple indoor units of varying capacity and configuration to one single condensing unit, resulting in simultaneous heating and cooling in different zones, with heat recovery form one zone to another. It is individual comfort control. Variable-speed-drive compressor technology (in the remote condensing unit) dynamically adjusts the system capacity to adapt to building load conditions, working in tandem with linear expansion valves at each indoor unit. The centralized control network ensures precise temperature control within each zone.

The Environmental Benefits The life-cycle environmental impact of any mechanical heating and cooling system is directly dependent on the carbon footprint of the energy source, as well as the total system performance characteristics – full and part load – in both heating and cooling modes. ARI studies indicate that a typical HVAC system operates at full load for only 1-2% of its life cycle. More detailed analysis illustrates that the majority of operating hours actually fall in the 40-80% total capacity range when in cooling mode. Mitsubishi Electric’s solution to optimizing system operation and reducing energy consumption is the variable refrigerant flow system that employ’s auto-tuning variable speed drive scroll compressors yielding high part load efficiency while also offering excellent seasonal energy efficiency. This performance optimization is achieved through dynamically matching daily or seasonal building load profiles. The ability to simultaneously heat and cool adjacent zones by energy transfer is another distinct advantage that the Mitsubishi Electric CITYMULTI VRF system has over other conventional approaches to HVAC design. An intermediate distribution compartment (BC Controller) facilitates the transfer of energy from the superheated refrigerant within the cooling zones to the refrigerant conditioning the heating zones. Where simultaneous heating and cooling are required the CITYMULTI variable refrigerant flow two pipe systems can transfer heat rejected from year round cooling zones (such as internal data rooms etc.) to perimeter zones which are calling for heating thereby reducing energy consumption. During shoulder season cycles, where simultaneously heating and cooling are more typical (east/west layouts, solar gain etc.), heat energy can be transferred between zones allowing the compressor to operate at part load (most efficient point of operation) while the indoor units are operating at full load (heating or cooling). Recently Mitsubishi Electric launched the ground breaking H2i Hyper Heating Inverter air-cooled product range which uses flash injection refrigerant circuits to secure 75% total heating capacity at -25 0C DB ambient temperatures with an efficiency rating of 1.5 COP – significantly higher than most conventional heating strategies. The Case Study Parameters The objective of this case study is to engage an industry recognized independent cost analysis team (AW Hooker – see profile for more details) to undertake a comprehensive first cost comparison through carefully considering the equipment costs, on site labor implications and commissioning costs for a range of HVAC system options as applied to  a high efficiency LEED certified commercial office building in Canada. The Evaluation Team AW Hooker Associates Ltd were founded in 1975 by Arthur W Hooker to provide superior quantity surveying and cost consulting services from an experienced and talented management team and staff of professional consultants. AW Hooker consultants use specialized knowledge, skills, and experience in a team effort in order to help clients make informed decisions at crucial stages in the development process of construction. For the purposes of this Case Study Mitsubishi Electric Canada worked with a senior consulting team led by Malcolm Yates (PQS CET) whose over 40 years of industry experience, including mechanical design consulting experience, proved invaluable during the development of this detailed case study. The Costing Analysis Technique Malcolm Yates and the team at AW Hooker employed the industry recognized elemental costing model to devise comparative cost estimates for multiple air conditions systems. A.W Hooker’s cost control process began with a deliberate gathering and extracting of all project information which might impact cost. The team worked to thoroughly understand each project’s requirements in order to properly interpret the design intent and application. This was followed with a methodical listing, tabulation and quantification process to which current market rates were applied. The result is a definitive cost report that compares the subject systems analyzed to the same level of costing parameters for a realistic and tangible comparative study. This can be relied upon as an objective, third party, independent report that tabulates and clearly identifies the costs of each system for comparative purposes The Building Template  The base building template for the case study is a 150,000 ft2 high tech, five storey office building designed to meet minimum LEED Gold standards. This building employs the world’s most innovative sustainable technologies to integrate its various internal systems into a highly efficient, cost effective working environment. The integrated systems offer the ability to monitor and micro-manage air quality, heating and ventilation, lighting, water usage and storm-water recycling. In this instance tenants will enjoy independent monitoring of their individual spaces to better regulate their specific needs. The Mechanical System Comparison The case study considered six mechanical heating and cooling system configurations for the template building as can be summarized in the following: Air-cooled Chilled Water System c/w VAV Distribution System Air-cooled Chilled Water System c/w Under Floor Air Distribution System Air-cooled Variable Refrigerant Flow System Water-cooled Chilled Water System c/w VAV Distribution System Water-cooled Chilled Water System c/w Under Floor Air Distribution Water-cooled Variable Refrigerant Flow System Heating loads are served by high efficiency gas fired condensing boilers except for the air-cooled variable refrigerant flow system where duct mounted supplementary heating elements are utilized. In the case of the water-cooled variable refrigerant flow system a reduced size of gas condensing boiler plant is provided to inject heat into the condenser water loop as required. The design cooling load for the building is approximate 375 tons and peak heating load 6000 MBH. Minimum ventilation air is provided by a standalone make up air unit with separate exhaust in each case to provide the ASHRAE recommended fresh air levels and air change rate within each conditioned zone. The Capital Cost Analysis The average installed capital cost for the air-cooled systems (chilled water and variable refrigerant flow system options) was estimated at $41.96 / ft2. The installed capital cost of the high efficiency air-cooled variable refrigerant flow simultaneous heating and cooling system was 5% lower than this average. Similarly the average capital installed cost for the water-cooled (chilled and variable refrigerant flow systems) was calculated at $44.96/ ft2. The installed capital cost for the high efficiency water-cooled variable refrigerant flow simultaneous heating and cooling system was typically within 10% of this value – the acknowledged margin of error attributed to the elemental costing technique. The on site commissioning cost for the two pipe simultaneous heating & cooling VRF air or water-cooled system was over 50% lower than the equivalent costs for any of the chilled water four pipe system design proposals. Capital Cost analysis is of course a fundamental initial consideration for any developer however building owners must adopt a long term perspective considering the life cycle impact initial capital cost driven design decisions can have. Life-Cycle Cost Analysis – A European Perspective  The most comprehensive real-world life-cycle analysis of variable refrigerant flow system performance come from Europe, where such technology has been considered mainstream for over 20 years. In 1998, an Italian bank, Unit Credit Banca, conducted energy retrofits on fourteen of its facilities. The capital projects team decided to retrofit 50 percent of the facilities with chiller/boiler four-pipe systems, and the remainder with VRF heating and cooling systems. Initial costs for both systems were similar, given the trade off’s between system design, on-site project management, mechanical infrastructure costs, and installation and commissioning time. Once in operational, the applications using the variable refrigerant flow systems consumed on average 35 percent less energy annually for heating and cooling. Annual maintenance costs were estimated to be 40 percent lower for VRF systems when compared to the chiller/boiler four pipe installations. Conclusion Comparing the total capital cost (equipment costs, installation and commissioning time on site etc.) of high efficiency innovative heating and cooling systems such as CITYMULTI variable refrigerant flow technology, to more conventional HVAC systems can offer a more definitive insight into the actual cost of ‘going green’ when applying mechanical HVAC systems to new build applications. CITYMULTI VRF technology can be applied to multiple building types and operations in both new and retrofit scenarios. Variable Refrigerant Flow systems yield significant operational cost benefits as well as capital cost parity or better. Going green is easier than you might think and Mitsubishi Electric are at the forefront in leading this shift in building system design as we continually strive to reduce our collective environmental impact.