Cold store design drawings: contents, process & how to read them

Cold storage design drawings (cold storage design drawing) is the technical document set that sets out, in one coordinated package, the architecture, the refrigeration system and the electrical control system of a cold store project before construction begins. A standard set comprises 5 core drawing groups: the architectural layout, the insulation section, the refrigeration P&ID, the electrical control diagram and the installation detail drawings. Each group serves a different stage, from permitting through to handover.

This article analyses the contents of each drawing group, the Q₁–Q₅ heat load formulas, the 5-step industry-standard documentation process, TCVN 6739:2016 and the mandatory international standards, and how to read the drawings when supervising construction. The content draws on over 20 years designing and building more than 300 industrial cold store projects by the engineering team at Tan Long, ranging from seafood stores in the Mekong Delta to GSP-compliant pharmaceutical stores in Ho Chi Minh City and Ministry of Health vaccine stores.

What is a cold store design drawing?

A cold store design drawing set is a detailed technical document that acts as the guide, providing every parameter needed to build an industrial refrigeration system. It sets out four core groups of data together: the architectural dimensions, the insulation material specifications, the equipment installation positions, and the refrigerant pipework diagram with the automatic electrical control system.

The essential difference from an ordinary building drawing is that a cold store design drawing has to show two specialist systems working together. The insulated envelope comprises the floor, the PU/PIR panel walls and the T-Light cold store doors. The refrigeration and electromechanical system comprises the compressors, industrial evaporators, condensers and the PLC control panel. Fail to calculate either part carefully and the drawing is not a sufficient basis for guaranteeing cooling performance or energy efficiency.

The role of drawings in an industrial cold store project

Cold store design drawings play four core roles across the life of an industrial cold store project. First, they are the legal basis for obtaining a construction permit, fire safety approval and handover certification once the work is complete. Second, they are the tool for controlling material costs precisely, through the accompanying bill of materials (BOM). Third, the parameters calculated in the drawings determine cooling performance and energy consumption over the store's whole life. Fourth, the document set is mandatory for later warranty work, repairs and refurbishment.

The standard number of drawings by store size

The number of sheets in a set of cold store design drawings is proportional to the size and complexity of the project. Practical experience from more than 300 projects at Tân Long gives the following standard distribution:

Every document is numbered systematically by revision (Rev 0, Rev 1…) and approved directly by the chief engineer before being issued for construction.

What does a set of cold store design drawings contain?

A complete set of cold store design drawings comprises five main groups, each serving a different stage in the life of the project — survey, permitting, construction and handover. The table below summarises the contents and the stage each group is used at.

The architectural layout plan

The architectural layout is the first and most important part of a cold store design set. It gives the overall top view, showing the total area and how the internal space is divided. The mandatory parameters are the actual dimensions (clear length × width × height), the position of the T-Light cold store doors, the antechamber, the forklift aisles and the position of the compressor pack.

One distinctive feature of Tân Long's design standard is that the no-stack zone is marked clearly on the layout drawing itself. The minimum clearance from goods to the panel wall is 150 mm (5.9 in) and to the ceiling 300 mm (11.8 in). Observing these clearances ensures the cold air circulates evenly, avoiding the uneven temperatures that spoil product.

The insulation section drawing

The insulation section drawing shows the detailed construction of the envelope both vertically and horizontally. It states the type of panel (PU or PIR), the insulation thickness from 75 mm to 200 mm (3–7.9 in) depending on the storage temperature, and the purpose-built floor construction. The drawing details the damp-proof layer, the floor ventilation sleeper system and the junctions between wall, floor and ceiling.

The underfloor ventilation sleeper system is the key technical element for a freezer store. Under Tân Long's technical standard, the sleepers are 300 mm (11.8 in) wide, 200 mm (7.9 in) high and installed at 400–500 mm (15.7–19.7 in) centres. A drawing missing this detail leads to the ground heaving after 6–12 months in service, from the large temperature difference between the deep-freeze store and the ground beneath.

The refrigeration P&ID

The P&ID (piping and instrumentation diagram) shows how the whole refrigeration cycle operates. It is not concerned with physical dimensions but with the logical connections between the main items of equipment: the compressors (Bitzer, Copeland), industrial evaporators, condensers, electronic expansion valves (EEV) and refrigerant receivers.

The drawing states the equipment models, the tag numbers (K for compressors, E for evaporators, C for condensers, V for valves) and the pressure measurement points. For industrial stores over 500 m³ (17,657 ft³), engineers favour NH₃ (ammonia) for its high efficiency and environmental credentials. Small and medium stores use R404A or R507 to balance the initial capital cost.

Power and control electrical diagrams

The electrical drawings in a cold store design set divide into two separate subsystems. The power circuit describes the connections from the main control panel to the high-power equipment through soft starters or variable frequency drives (VFD), ensuring the starting current does not cause a voltage dip on the supply.

The control circuit covers the wiring of the PT100 temperature sensors, the pressure sensors and the PLC control panel modules. This is the brain of the system, monitoring operation and linking data remotely through SCADA or a Modbus RTU port, letting the owner manage the store from a mobile device at any time.

Installation detail drawings

Installation detail drawings show the parts that are hardest to build, at an enlarged scale of 1:5 or 1:10, so the installation team can work accurately on site. The mandatory details include the rubber gasket construction of the T-Light cold store door, the position of the anti-frost gasket heater, the anti-vibration mounts for the compressor pack and the supports for the refrigerant pipework.

Missing installation detail drawings is a common failing on projects handled by inexperienced designers. The consequences are doors that do not seal, gaskets that ice up, and compressors that vibrate and crack copper pipework after only 3–6 months in service.

How the heat load calculation is presented on the design drawings

Heat load is the total quantity of heat the system must remove from the store per unit of time, shown directly on the design drawings in the capacity calculation table. This figure determines the compressor and evaporator capacities selected for the project. A drawing without a heat load calculation means there is no technical basis for the entire refrigeration system behind it.

The total heat load formula Q = Q₁ + Q₂ + Q₃ + Q₄ + Q₅

Total heat load is calculated by summing the five main heat gains:

Q = Q₁ + Q₂ + Q₃ + Q₄ + Q₅ (kW)

The table below analyses the meaning and the average share of each component in the total heat load:

Q₅ applies only to stores holding fresh fruit and vegetables and can be ignored for frozen seafood and frozen meat stores. The sub-formula Q₁ = k × F × Δt, where k is the panel's heat transfer coefficient (W/m²K), F is the heat transfer surface area (m²) and Δt is the temperature difference between inside and outside the store (°C).

Indicative heat load table by temperature and store type

Experience from more than 300 projects at Tân Long allows a quick conversion to an average heat load by store type. The table below helps investors estimate the compressor capacity needed before going into detailed calculations:

Note that these indicative figures apply to southern Vietnamese climate conditions (outdoor temperature 35–38°C, humidity 75–85% RH). A cold store in northern Vietnam in winter may need 10–15% less than the indicative heat load.

Safety factors and how to select compressor capacity

Once the total heat load Q is calculated, the engineer multiplies by a safety factor to determine the compressor capacity to install. Tân Long's standard safety factor ranges from 10–15% for industrial stores in temperate climates to 15–20% for stores in the humid tropical southeast and the Mekong Delta.

As a worked example, take a 200 m³ (7,063 ft³) seafood freezer store in Cần Thơ at a storage temperature of −20°C (−4°F). The total heat load calculated by the Q₁–Q₅ formulas comes to around 20 kW. Multiplied by a 15% safety factor for the hot, humid Mekong Delta, the minimum compressor capacity required is 20 × 1.15 = 23 kW. The engineer would then select a Bitzer or Copeland compressor with a nominal rating of 25 kW to give an operating margin at the peak of the hot dry season.

Tân Long's 5-step standard process for producing cold store design drawings

Tân Long's process for producing a set of cold store design drawings is standardised in five rigorous steps, from the existing-conditions survey through to issue for construction. Each step produces specific outputs, ensuring consistency throughout and allowing quality control at each handover point.

Step 1 — survey the site and gather the input data

At the first step, the design engineer measures the site dimensions to a permitted technical tolerance of ≤ 3 mm over 2 m (≤ 0.12 in over 6.6 ft). Beyond the geometry, the survey team collects key technical data including the required floor loading (≥ 1.5 tonnes/m², equivalent to 307 lb/ft², for an industrial store) and the moisture content of the ground. Where ground moisture exceeds 60%, specialist damp-proofing is recommended before the panels go up.

The most important data is about the goods to be stored: the daily volume in and out, the temperature required and the storage duration. This is the basis for the heat load calculation at the next step. The outputs of the survey step are an existing-conditions survey sheet signed by the client, site photographs and a preliminary dimensional sketch.

Step 2 — calculate the heat load and select the equipment

From the survey data, the engineer builds an Excel heat load calculation using the Q₁–Q₅ formulas set out above. Each component is calculated separately for each wall, the ceiling and the floor using Q = k × F × Δt. The aggregated result gives the total heat load for the whole store.

The compressor and industrial evaporator capacities are selected with a 10–15% safety factor, to ensure reliable operation in Vietnam's extremes of weather. The outputs of this step are the approved Excel heat load calculation and a preliminary bill of materials (BOM) with technical specifications.

Step 3 — produce the layout plan and insulation section drawings

The engineer produces the architectural layout in AutoCAD at a standard scale of 1:50 or 1:100 depending on the size of the project. The drawing is clearly separated into layers for the architecture, the panel setting-out and the equipment positions, to make later revisions straightforward.

The insulation section drawing details the floor, wall and ceiling junctions. The T-Light cold store door installation details and the underfloor ventilation sleeper system are enlarged to 1:5 or 1:10 so the installation team can build them accurately. The output is 4–6 A1 sheets of completed layout and section drawings.

Step 4 — produce the refrigeration and electrical diagrams

The refrigeration engineer works from the selected equipment list to produce the P&ID to ISO 1219 or the ASHRAE Handbook. Every valve, pipe run and measurement point is given a clear tag number (K-01, E-01, V-01…) so materials can be traced easily during construction.

In parallel, the power and control electrical diagrams are produced to IEC 60364. The title block on each electrical sheet states the operating voltage, the frequency and the cable type suited to the PLC control panel system. The output is 3–5 A1 sheets of P&ID and electrical diagrams plus a detailed bill of materials.

Step 5 — check, approve and issue the document set

A set of cold store design drawings goes through three rounds of quality control before being issued for construction. In the first, the design engineer self-checks the consistency between sheets. In the second, the design manager reviews independently to catch technical errors. In the third, the client reviews and signs off the set before work begins.

The issued set states the revision clearly (Rev 0 for the first issue, Rev 1, Rev 2 for subsequent changes). Only drawings stamped “Approved for construction” are formally released to site. Every change after approval must be captured in a new revision and re-signed, ensuring full transparency and accountability from the designer to the client.

Mandatory technical standards for cold store design drawings

Industry-standard cold store design drawings in Vietnam comply with both Vietnamese standards (TCVN) and international standards. Compliance is not only a legal requirement but the precondition for the project passing inspection and being handed over. The table below summarises the mandatory standards for each drawing group.

Vietnamese TCVN standards applying to refrigeration systems

The foundation standard for refrigeration systems in Vietnam is TCVN 6739:2016 (equivalent to ISO 5149) on the safety of refrigeration systems and refrigerants. It sets out the requirements for design, manufacture, installation, operation and periodic inspection of systems using A1, A2, A2L and A3 refrigerants. Every industrial cold store design drawing must cite this standard in the title block.

TCVN 7437:2004 specifies the symbols for electrical equipment on drawings, and applies to both power and control diagrams. The standard symbols include Q (circuit breaker), K (contactor), F (fuse), M (motor), S (switch), and so on.

International standards: ISO, ASHRAE, EN, ASME

Industrial cold store design drawings also reference international standards in parallel, to ensure international compatibility:

Particular requirements for GSP pharmaceutical stores and HACCP food stores

Pharmaceutical cold stores follow the GSP/GDP standards (WHO Technical Report Series 961). A pharmaceutical cold store design set must additionally include drawings for the continuous temperature monitoring system: data logger positions to a mapping of at least 9 measurement points, the SCADA data communication diagram and the design of the temperature alarm zones. This supplementary drawing group does not appear in an ordinary food store set.

Food cold stores to HACCP and ISO 22000 require drawings showing clean/dirty one-way flow, the positions of pass-boxes and hand-wash points, and floors draining at a minimum 2% fall. Stores certified for seafood export to the EU, the US or Japan must also include drawings of the CIP (clean-in-place) automated cleaning system.

Cold store design drawings by type of goods stored

There is no single template for cold store design drawings that fits every type of goods. Each product imposes its own technical requirements on temperature, humidity, contact materials and monitoring. The four specialist drawing groups below represent the four most common cold store applications in Vietnam.

Drawings for seafood cold stores and blast freezers

Drawings for seafood cold storage are distinctive in dividing the space into three separate functional zones: raw material intake, the rapid freezing chamber (IQF — individual quick freezing) and the long-term frozen store. The freezing chamber reaches −35 to −40°C (−31 to −40°F), with IQF freezing time reduced to 20–30 minutes per batch of shrimp or fish fillets. The frozen store holds −18 to −25°C (0 to −13°F).

The section drawing requires 200 mm (7.9 in) ventilation sleepers and an electric underfloor heating system to prevent ground freezing. The insulated panel specified is PIR at 150–200 mm (5.9–7.9 in) for the freezing chamber. The electrical system needs an automatic defrost cycle integrated at 6-hourly intervals.

Drawings for GSP-compliant pharmaceutical and vaccine cold stores

Drawings for pharmaceutical cold store and vaccine stores comply strictly with the GSP/GDP standards (WHO). Storage temperatures are set in two bands: 2–8°C (36–46°F) for vaccines and biologicals, and 15–25°C (59–77°F) for general pharmaceuticals. Humidity is held at 45–65% RH, and the drawings must show the dehumidifier system.

The distinctive feature of a pharmaceutical store set is the mandatory mapping and monitoring sheet. Mapping requires at least 9 measurement points for stores under 50 m³ and 15–25 points for stores over 100 m³, distributed evenly on a 3D grid. Each point corresponds to a PT100 or NTC sensor logging every 5 minutes, with data transmitted to SCADA and retained for at least 5 years for audit purposes. The drawings also show the position of the UPS.

Drawings for processed food and fresh produce cold stores

Drawings for processed food and fresh produce cold stores are distinctive in requiring high humidity and ethylene control. A produce store holds 0–5°C (32–41°F) at 85–95% RH, and the drawings must show the ultrasonic humidifier system and forced ventilation. Stores for late-ripening fruit (bananas, mangoes, avocados) also need an ethylene (C₂H₄) control system to regulate the rate of ripening.

The drawings follow HACCP principles with clear clean/dirty separation, floors falling at ≥ 2% towards the drainage channels, and a CIP system for routine cleaning. The T-Light cold store door is usually specified as a high-speed PVC roller door, to reduce heat loss where forklifts pass in and out continuously.

Drawings for chemical and specialist industrial cold stores

Chemical and specialist industrial cold store drawings require corrosion-resistant materials and ATEX explosion protection for flammable chemicals. The walls and ceiling normally use 304 or 316 stainless steel in place of ordinary colour-coated steel. The electrical system must be Ex-proof, with explosion-proof terminals, light fittings and circulation fans.

The drawings clearly show the emergency ventilation system, with an air change rate of 10–12 store volumes per hour, activated automatically when the sensors detect a leak. Large chemical stores also require drawings of the automatic sprinkler system and a toxic gas alarm centre connected to the central PLC control panel.

How to read cold store design drawings

Reading cold store design drawings is an essential skill for investors and site supervisors controlling the quality of the installation in practice. The documents are technical, but the four reading principles below let you grasp the core information through the standard symbol conventions.

Reading the title block, drawing scale and line conventions

The first step with any cold store design drawing is to look at the title block in the bottom right corner. It carries three decisive pieces of information: the drawing scale (1:50 or 1:100 for layouts; 1:5 or 1:10 for details), the revision number and the formal approval date. Any drawing missing these three is not valid for construction.

Line conventions help you visualise the space. Heavy solid lines show elements at the cutting plane or below floor level, such as the perimeter walls and the T-Light cold store doors. Dashed lines indicate equipment mounted at high level, such as ceiling-suspended industrial evaporators. Chain-dotted lines are used for symmetry axes and wall centrelines. The clear internal dimensions of the store are normally 200–400 mm smaller than the external dimensions.

Reading the architectural layout and insulation section

On the layout plan, the standard reading order is to establish north first, then follow the forklift aisles, the entry and exit door positions, the antechamber and the compressor pack. The clear length × width × height dimensions are given in a box or along the dimension lines. The numbered boxes correspond to the equipment schedule attached.

The insulation section is read from the outside in. The outermost layer is colour-coated or stainless steel, then the PU/PIR insulation, then the internal lining sheet. The underfloor ventilation sleepers are shown as inverted U shapes, with their dimensions and centre-to-centre spacing noted. The underfloor heating element sits between the dry sand layer and the structural concrete.

Reading the P&ID in the direction of refrigerant flow

The P&ID is read in the direction of refrigerant flow, to understand how the whole system operates. The cycle starts at the compressor pack, passes along the discharge line (DL) to the condenser, on through the receiver, the electronic expansion valve (EEV), and finally to the low-pressure evaporator. From the evaporator the refrigerant returns to the compressor along the suction line.

Pipework designations to note: SL (suction line) for the low-pressure suction, DL (discharge line) for the high-pressure discharge, LL (liquid line) for the liquid. Pipe diameters are given in DN (mm) or inches — DN25 equals 1 inch, DN40 equals 1-1/2 inches. Each item on the diagram is given a tag number such as K-01 for compressor no. 1, E-01 for evaporator no. 1 and C-01 for condenser no. 1, for exact cross-reference to the equipment schedule.

Checking consistency between drawing sheets

The most common failing in a design set is inconsistency between sheets. When reviewing a set, the site supervisor should cross-check three key things. First, the store dimensions on the layout and the section must match exactly in length, width and height. Second, the compressor capacity and model on the P&ID must match the BOM and the contractor's capability documents. Third, the cable sizes on the electrical diagram must suit the equipment ratings in the control panel, avoiding both overload and wasted budget.

This consistency check not only ensures safe operation but provides the legal basis for the inspection and handover stage of the cold store project.

Common errors in cold store design drawings and how to avoid them

Practical experience from more than 300 cold store projects at Tan Long shows five groups of errors recurring most often in design documents. Each has its own construction consequence and its own specific preventive measure at the drawing stage.

The most dangerous error is failing to account fully for the internal load (Q₄). On a 300 m³ (10,594 ft³) −20°C (−4°F) freezer store in Cần Thơ that the Tân Long team was called in to repair in 2023, the original design engineer had ignored the heat from 3 electric forklifts working inside the store, each giving off 2.5 kW. The result was a compressor running 22 hours out of 24 and still lacking the capacity to pull the temperature below −15°C (5°F) — 5°C above the design requirement. Putting it right by upgrading the compressor 40% and reworking the pipework cost more than 450 million VND and 2 months of lost operation.

A second, no less serious, error occurred at a GSP-standard pharmaceutical store in a Ho Chi Minh City industrial park in 2024. The previous designer had omitted the temperature mapping and monitoring drawing, so at the GSP audit the inspection team refused certification. The owner had to suspend operations for 2 months while the Tân Long team redrew the monitoring layout with 15 measurement points, installed data loggers and re-ran the IQ/OQ/PQ validation — more than 380 million VND outside the budget.

As-built drawings after cold store construction

An as-built drawing is the document set recording the works as actually constructed, once the cold store has been inspected and handed over. It is a mandatory legal document for later warranty work, maintenance, repairs and refurbishment. It differs from the original design drawing in capturing every change that arose during construction.

The content that must be updated includes the actual positions of the valves and refrigerant pipe runs, the actual dimensions of the store once the panels are up (typically 10–30 mm different from the design because of construction tolerances), the positions of the temperature measurement points at handover, and any material changes against the original BOM. The as-built drawing carries an “As-Built” stamp with the signatures of the site supervising engineer and the client.

Tân Long hands over a complete as-built document set to the client on every project, comprising A1 prints and the original CAD files (.dwg), accompanying PDFs, the equipment warranty book, an operating manual written specifically for that store, and the IQ/OQ/PQ validation records for GSP pharmaceutical stores. The whole set is also archived on the server.

Having covered the contents, the process, the applicable standards and how to read a set of cold store design drawings, a few concepts still cause confusion, along with practical questions investors often ask before signing a construction contract. The section below clarifies them, so you have the full picture before starting a project.

Design drawings, shop drawings and as-built drawings compared

The three terms “design drawing”, “shop drawing” and “as-built drawing” are often confused on industrial cold store projects. In fact they are three different documents, appearing at three different stages in the life of a project, produced by three different parties for three distinct purposes.

A shop drawing is produced by the installation contractor from the original design drawing, showing technical details at an enlarged scale for the installation of each specific item. A shop drawing does not replace the design drawing; it adds detail the designer did not go into. The as-built drawing is produced last, capturing every change against the design drawing for later warranty and refurbishment purposes.

Get a complete set of cold store design drawings for your project

Cold store design drawings are the foundation of quality control, from before construction through to after handover. A complete set comprises five core drawing groups: the architectural layout, the insulation section, the refrigeration P&ID, the electrical control diagram and the installation details. The standard production process runs through five steps, from the heat load survey to approval and issue, complying with TCVN 6739:2016 and the ISO, ASHRAE, EN and ASME international standards. The as-built drawing set after construction is a mandatory document for warranty and long-term operation.

Reading and understanding cold store design drawings lets an investor supervise construction actively and catch errors before they affect the quality of the works or its operating performance. Contact Tân Long's engineering team today for a free site survey, preliminary design drawings and a detailed quotation for your cold store project — from a GSP-compliant pharmaceutical chill room to a seafood blast freezing store for export.

Related pages

• Cold store classification: 5 technical criteria and how to choose the right type
• Storing dried squid in bulk in a cold store: temperature and humidity standards
• Cold store repair: how to identify faults and the expert troubleshooting process
• How to store beef jerky in bulk: temperature standards and industrial cold storage systems
• Tan Long industrial cold storage

Review & Expert Advice

Engineer Nguyen Toan Thinh (Technical Director)

With over 18 years of practical experience in directing, consulting, designing, and constructing heavy industrial refrigeration systems, ASRS automated warehouses, and IQF freezing systems across more than 29 major national projects.

👉 View expert's profile | 📞 Technical support hotline: 0933 357 058