Air conditioning system

What is included in the design of air conditioning systems?

Design AC system is being developed as part of the subsection IOS 5.4 “Heating, ventilation and air conditioning, heating networks” according to Decree of the Government of the Russian Federation No. 87 dated 16.02.2008 (rev. 2023). The two stages - DD for examination and WD for installation and commissioning - differ in the degree of detail and the composition of documents.

Design documentation stage includes:

• An explanatory note justifying the chosen air conditioning scheme, describing the technical solutions adopted and the parameters of the design microclimate for GOST 30494-2011 And SanPiN 1.2.3685-21
• Calculation of the heat load on the air conditioning system: heat gain through the building envelope, from solar radiation, from people, lighting and equipment according to the methodology SP 60.13330.2020 Appendix A
• Justification for choosing the AC system type (split, multi-split, VRF/VRV, chiller-fan coil, central air conditioner) with a technical and economic comparison of options
• Schematic diagrams of refrigeration supply: refrigerant or coolant lines, layout of outdoor and indoor units (for VRF) or chiller, fan coils and pump group
• Refrigeration supply diagram with hydraulic parameters (for chiller-fan coil systems)
• Tasks for related sections: KR (loads from outdoor units, chillers), EL (power, reliability category), AS/AD (control algorithms, integration into BMS)
• Energy efficiency section: justification of seasonal EER and SCOP coefficients, comparison with the base case

The WD Stage Includes:

• Working drawings of refrigerant or coolant pipeline routes on plans M 1:50, axonometric diagrams
• Equipment specifications: external and internal VRF/multi-split units with selection according to the thermal load of each room, chillers, fan coil units, pump groups, expansion tanks, heat exchangers
• Installation diagrams: nodes for passage of pipelines through structures, fastening of external units with vibration insulation, drainage systems
• Automatic control schemes for SCR: algorithms for operation in cooling, heating and ventilation modes, signal tables for BMS or centralized control
• Bills of quantities, summary statements of equipment and pipelines
• Programs and methods of commissioning work (PW) for air conditioning systems

Comparison of stages design documentation and working documentation for air conditioning systems

What air conditioning systems are used depending on the type of object?

The choice of SCR scheme is a key design decision that affects capital costs, operating costs and ease of management over the entire life of the building. AYU-Project selects the type of system based on the results of calculating the heat load, analyzing architectural solutions and requirements for microclimate control in each zone.

• Split systems and multi-split systems - used for individual rooms or small objects with an area of up to 300-500 m²; easy to install, do not require a machine room; do not provide fresh air and require a separate ventilation system
• Multizone VRF/VRV systems - the most common solution for office, hotel and retail buildings with an area of ​​500-5 000 m²; one external branch serves up to 64 internal units of various types (wall-mounted, cassette, duct, floor-mounted); length of refrigerant lines - up to 165 m, height difference - up to 90 m; the coefficient of joint operation up to 1,3 allows you to reduce the total power of outdoor units
• Chiller-fan coil systems - optimal for large facilities with an area of 3 000 m²: office centers, hotels, shopping centers; the coolant (water or water-glycol mixture) is distributed by pumps, fan coil units are installed in each room; configuration flexibility is practically unlimited; require a machine room for the chiller and pump group
• Central air conditioners (TsK) - provide air treatment (cooling, heating, humidification, filtration) as part of the air handling unit; used in sales areas, auditoriums, production facilities; do not provide individual regulation by zones without additional VAV valves
• Precision air conditioners - for server rooms and data center: maintain temperature with an accuracy of ±0,5 °C, provide round-the-clock operation 24/7 with heat excess up to 100 kW/m²

How is the heat load on an air conditioning system calculated?

Calculation of the heat load is the foundation of the SCR project: it determines the power of the equipment and, therefore, the entire cost of the system. Underestimating the load leads to overheating of the premises, overestimating it leads to excessive capital costs and frequent start-up cycles, reducing the life of the compressor.

AYU-Project calculates the heat load using the following components in accordance with SP 60.13330.2020 Appendix A:

• Heat gains through building envelopes - determined by the difference in temperatures of external and internal air, area and thermal resistance of structures, taking into account the orientation of facades along SP 131.13330.2020
• Heat gain from solar radiation - through glazing, taking into account orientation, type of glass, solar shading devices and latitude of construction; one of the key factors for southern and southwestern facades with a large glazing area
• Heat gains from people - according to standard values of sensible and total heat transfer per person, depending on the type of activity (rest, office work, physical labor) according to GOST 30494-2011
• Heat gains from lighting and equipment - from lamps (the share that turns into heat), servers, technological equipment; especially significant for data center and production facilities
• Heat gain from supply air - in buildings with combined heating and air conditioning systems, the supply air during the warm period carries an additional heat load, which is distributed between the ventilation systems and SCR
• Final selection of equipment - based on the calculation results, AYU-Project generates a technical specification for the selection of equipment indicating the cooling capacity, coolant temperature range and energy efficiency class

Typical mistakes in designing air conditioning systems

A significant part of the complaints against air conditioning systems in already operating buildings are the result of errors made precisely at the DD stage, and not during installation. AYU-Project excludes them due to mandatory double standard control of calculations and BIM coordination.

• Underestimation of heat gains from solar radiation - the most common mistake for glazed office facades; when calculating without taking into account the orientation of the building, the load on AC system is underestimated by 20-35%, which leads to overheating in the summer
• Heat transfer from fan coil fans and precision air conditioners is not taken into account - fan power is the excess heat in the room; when summing up the loads, its omission leads to an underestimation of the required cooling capacity
• Combining zones with different modes into one VRF branch - the northern and southern rooms of the same floor have opposite regimes: some require cooling, others require heating; combining into one system without a four-pipe circuit or systems with heat recovery is unacceptable
• Ignoring Refrigerant Route Restrictions - exceeding the standard length of the VRF system route (manufacturers limit it to 150-165 m) reduces system performance and violates warranty obligations; AYU-Project respects manufacturer restrictions
• Lack of drainage schemes - in WD, without detailed drainage pipelines, condensate from the internal units ends up on the ceiling structures; AYU-Project studies the drainage of each block in axonometric diagrams
• Inconsistency of AC system with ventilation - if the air conditioning system and ventilation system are designed independently, the thermal loads are duplicated or contradict each other; AYU-Project designs HVAC as a single complex

Integration of air conditioning systems with building engineering systems

The air conditioning system is not autonomous: its efficiency is 30-40% determined by the quality of its interface with ventilation, heating, power supply and automation. AYU-Project designs AC system in conjunction with all adjacent sections with the issuance of joint tasks at the DD stage.

Integration with ventilation and heating

For office buildings and shopping mall AYU-Project designs four-pipe fan coil systems that allow you to simultaneously cool some areas and heat others - this is especially important in the off-season, when the southern facades overheat, and the northern ones still need heat. The heat balance of the building is calculated jointly according to sections HVAC and AC system in order to eliminate the competitive operation of air conditioners and heating devices.

Automation and BMS

The control of VRF systems and chillers is integrated into the BMS via Modbus, BACnet or KNX protocols. AYU-Project develops algorithms for controlling summer/winter modes, zone operation schedules and emergency blocking based on an APS signal, as well as a task for the automation section (ATC) with signal tables for each ACS circuit.

Why choose AYU-Project to design air conditioning systems?

AYU-Project designs AC system as part of an integrated HVAC system: heat load calculation, scheme selection, architecture linking and integration with BMS are performed by one command, which eliminates inconsistencies between sections and expert comments on related solutions.

Specific benefits:

• SRO Design Authorization capital construction projects, including technically complex ones
• Complete calculation set in DD: heat load for each room, comparison of AC system schemes, justification of energy efficiency class - no additional charge
• BIM design in Revit and MagiCAD: coordination of refrigerant and coolant routes with adjacent sections KR, VK, EO, OV - collisions are eliminated at the DD stage, and not at installation
• Fixed price contracts: the cost is not revised during the development process
• Free Revisions in Response to Expert Review Comments: adjustments DD based on the results of the examination are included in the contract
• Experience Across Projects of Various Scales: from server rooms with precision air conditioning to shopping mall with an area of 30 000+ m² with chiller-fan coil and VRF systems

What standards govern the design of air conditioning systems?

The design of AC system is governed by federal codes of practice, sanitary standards and national standards in the field of construction and microclimate. All documents are applied in the version valid on the date of development DD.

Current list of regulatory documents:

• Federal Law No. 384-FZ “Technical Regulations on the Safety of Buildings and Structures” from 30.12.2009 (as amended) - establishes general requirements for engineering systems, including AC system
• SP 60.13330.2020 “Heating, Ventilation and Air Conditioning” (updated edition SNiP 41-01-2003, with Amendments No. 1-5) - the basic set of rules regulating the parameters of the design microclimate, calculation of the heat load, requirements for refrigeration supply and equipment AC system
• SP 131.13330.2020 “Construction Climatology” (updated version SNiP 23-01-99*) - calculated parameters of outdoor air (temperature, humidity, solar radiation) for the warm and cold periods of the year
• GOST 30494-2011 “Residential and Public Buildings. Indoor Microclimate Parameters” - standardized values of temperature, humidity and air speed in the service area; basis for setting design parameters of SCR
• SanPiN 1.2.3685-21 “Hygienic standards and requirements for ensuring the safety and (or) harmlessness of environmental factors to humans” - permissible microclimate parameters in workplaces, standard values for residential and public buildings
• Decree of the Government of the Russian Federation No. 87 from 16.02.2008 (ed. 2023) “On the composition of sections of project documentation” - regulates the composition of subsection IOS 5.4 (HVAC) at stage DD, including refrigeration and air conditioning
• GOST R 58274-2018 (EN 14511-1-4:2013) “Air conditioners, liquid coolers and heat pumps” - test methods and classification of equipment used in the design of AC system
• SP 50.13330.2012 “Thermal protection of buildings” - characteristics of enclosing structures used in calculating heat input into rooms through walls and coverings
• GOST 12.1.005-88 “General sanitary and hygienic requirements for air in the working area” - standardization of air parameters at production facilities, which determines the requirements for technological air conditioning
• SP 54.13330.2022 “Residential multi-apartment buildings”, SP 118.13330.2022 “Public buildings and structures” - special microclimate requirements for residential and public buildings, respectively

Air-conditioning design scope and schedule

The scope and schedule for air-conditioning design documentation and working documentation are determined by system-specific factors:

• Type of selected SCR scheme - the project of a VRF system, a chiller-fan coil system and precision air conditioning data center fundamentally differ in the complexity of the calculations and the volume WD
• Number of air conditioning zones and indoor units - each zone requires a separate calculation of the thermal load and selection of equipment; for VRF systems - calculation of route lengths and collaboration coefficient
• Availability of engine room - for chiller-fan coil systems, it is necessary to study the layout IHS/MO, hydraulic calculations, tasks KR and EL
• Requirements for integration with BMS - development of signal tables, control algorithms and automation circuits increases the volume of WD
• Special microclimate requirements - medical facilities, clean rooms, data center require an expanded range of calculations and approvals
• Design stage - only DD, only WD or combined development DD+WD

Approximate calculation - through the online calculator on the website.

To prepare an accurate commercial proposal, the application must indicate: the type and function of the facility, the total area of ​​air-conditioned premises, preferences for the AC system scheme (if any), the presence of a machine room or restrictions on the placement of outdoor units, the design stage (DD, WD or DD+WD). The initial consultation is free, and we work across Russia remotely.