Weak current College】 【HVAC design should pay attention to some key issues (1).

Design on HVAC project design and bad relationship between the success or failure. In recent years, with the rapid development of science and technology, as well as on energy saving and environmental protection requirements and continuous improvement, HVAC design programme in the new booming, for the same design projects, often can have several, or even dozens of dozens of different design options to choose from, the designers had to do a lot of comparison and selection work, design is becoming the technical and economical comparison affect HVAC design quality and efficiency of an important work. HVAC design scheme for the evaluation of a number of factors, some of the factors is difficult to quantitative expression, many factors are not comparable, each design programmes often has its own advantages and disadvantages, faced with numerous design options, consider the problem of different views of the parties, always different, even quite different. Currently in the design of some of the comparison of disarray that designers do. How HVAC design scheme for comparison and selection of science is HVAC design professionals in the actual design work often encountered in a key technical challenges. Author based in the design, plans and programmes for the assessment of some experience, on HVAC design scheme comparison in some superficial analysis of the issues.

1, a feasibility issues

To meet the requirements, this is the programme feasibility should be considered a major problem. Designs should be consistent with State and local government regulations and requirements, including requirements relating to environmental protection; design should be able to meet the relevant requirements (such as electricity, gas supply, water supply, heating, etc.) and to take into account these conditions for long term, changes in circumstances. Such as the use of water-source heat pump design should consider local geology, groundwater resources of situation and trends, the heat load in winter and summer cooling load imbalance caused by thermal (cold) cumulative effects issues. For parameters such as temperature and humidity higher or special technology of HVAC design project, you should design for the whole year cycle analysis to ensure that its year-round outdoor weather conditions of adaptability. For those unable to use standard equipment of special circumstances, non-standard equipment should be put forward detailed parameters of the request, and the parameter requirements should be reasonable and practicable. Whether there is enough room area is also a feasibility assessment design programme must take account, in particular for some renovation works and the building area is strained. For some requirements as a guarantee for indoor air parameters of important projects, as well as air conditioning system downtime will have a serious loss of places, such as Cosmodrome, consideration should be given to the system device and backup issues system feasibility analysis. In this case, the outdoor weather parameters and the determination of the safety factor should also be a special consideration.

2. economic comparison problems

Economic comparison is HVAC plan comparison in considering the issue of a maximum. When comparing the economy first note baseline must be consistent. Should adopt the same design requirements, usage, device classes, energy prices, comfortable situation, beautiful situation, to compare the baseline conditions, so as to ensure that the comparison of scientific programmes and rationality. If you use brand-name equipment and the use of low quality equipment programme for economic comparison, it is clearly unreasonable; if you do not consider the difference between, on the comfort of a fresh air supply and no fresh air supply economic comparison of programmes is clearly impossible to make the right choice; if you do not consider the appearance and comfort for economic comparison, centralized air conditioning programme was clearly unfair.

Once the investment is the investment side of the main concerns of a parameter in the calculation of the investment should be fully accurate and not leak. HVAC design scheme of an investment not only includes a variety of equipment, pipelines, material investment, and should include all related fees and charges (such as thermal network access fees, electricity equipment MEF, natural gas sources, etc), the appropriate installation and commissioning costs related to the project management and other charges related to water treatment and distribution and control of investment, the engine room construction investment and the cost of the corresponding outdoor pipelines, while those in the actual design work can easily be missed. As a result of the same kind of equipment manufacturers, prices vary, so different when comparing the programme economics computing devices of average prices of price should be used.

These are direct costs, in some cases indirectly benefit should also be considered. Such as hotels, restaurants, office buildings in the area of the air conditioning room save as commercial housing can yield benefits. If you take a loan for construction, comprehensive economic comparison you should also consider the loan interest rate and repayment period, and other dynamic elements.

Operating power consumption and operating costs are the HVAC design technical and economical comparison must consider important parameters. Operating power consumption in addition to calculating HVAC host (boiler and chiller, etc.) of energy consumption, but also calculate other assistive device (such as fans and pumps, etc.) of energy consumption. You cannot simply follow the equipment nameplate power and run time to calculate the energy consumption of the product and should take into account seasonal variations throughout the year, the actual load of the building, taking equipment non-standard State of efficiency. Office building, teaching building, Office building and a swimming pool, and other buildings of HVAC equipment is usually intermittent operation, its running time should be less downtime after the actual run-time. In the calculation of different regions and different times, different times of the various energy prices may vary. As a result of factors and uncertainties more, how to accurately calculate building HVAC equipment as a whole the actual energy consumption and operating costs, there is still a not completely solve technical challenges. Operating costs in addition to the energy consumption costs such as electricity, gas, coal, gas costs, they should also include consumption of water, labor, etc.

In comparison, avoid economical map easy can be directly used for manufacturers of comparative data and results. I have found that electric heating of operating costs, three different equipment (electric boiler, water source heat pump and gas-fired heating boiler house) manufacturer's calculations. Through its detailed reconciliation of the calculation, discover different equipment manufacturers due consideration in the calculation of different angles, there are beneficial to your own product, is not conducive to othersProduct failure or assumptions. The designer should give enough attention to, the data provided by the manufacturers should be careful analysis and verification.

Economic comparison of the design should be considered for investment, operating costs and equipment service life, in the same cycle as the basis for the calculation of the overall economy, and not simply a quote based on the device. For both heating and air conditioning requirements, consideration should be given to winter and summer equipment utilization issues comprehensive economic comparison of winter and summer. For domestic hot water can be cum for projects, should be considered domestic hot water supply of investment and consumption.

3. regulatory and operational issues

HVAC system capacity is usually the most throughout the year by close to unfavourable meteorological conditions, the system should have better performance in order to adapt to changes in load throughout the year. Adjust the performance of system programs, such as the use of VAV system and VRV inverter air conditioner system, an investment normally higher but less energy consumption, in economic terms and should be considered when comparing these factors. For some time use of office buildings, office buildings and teaching building, the design should be able to adapt to its night-time is not working in regulatory requirements.

Design management operation convenience is very concerned about the user. Air conditioning system automation level, you can reduce the number of managers and intensity, resulting in reduced labor costs, but make an investment, the operator's quality requirements. Air conditioning system is the use of automatic control, according to the actual circumstances and requirements, technical and economical comparison to determine. For large air conditioning systems and need regular adjustment and control of devices more engineering, automatic control, should be adopted to reduce the operational management of the workload. But the automatic control system should be simplified in order to improve system efficiency and feasibility. For only only seasonal transition operations would not be appropriate for the use of automatic control valves. For some sections not simultaneously use of buildings or parts of a rented to the different units, the system sets the commercial buildings should take into account the respective management control and operating costs are paid statistics.