Calculate / Heat Loss and Savings

Heat Loss and Savings

Calculators Heat leaving the surfaces in a year, its cost, and the gain over a bare steel envelope.

U-value Calculator Loading Quantities Panel Area Calculator Panel Weight Heat Loss and Savings

A significant part of the heat lost from a building in winter goes through the envelope. This calculation gives the heat leaving the panel-clad surfaces by conduction in a year and its money value, and sets beside it the loss those same surfaces would have if they were clad in uninsulated steel.

Climate The figure is the average external temperature in winter (December to February). Monthly values from TS 825 Annex B.2. Building type Selecting one sets the internal temperature to its own value: warehouse 18, commercial 20, hospital 22 °C. Internal temperature °C Comes with the building type and can be changed. The temperature held inside in winter. Energy price The price per kWh of the energy used for heating, the unit price on your bill. The currency is selected on the right.

Distribution of the annual loss across the surfaces

Roof%5436,050 kWh

Wall%3020,367 kWh

Floor%1610,868 kWh

The percentages show which surface the heat lost in a year leaves through; together they add up to 100. Whichever surface carries the largest share, increasing the thickness there gains the most.

PIR

SurfaceWhere the panel sits on the building. CoreThe core of the panel. The thermal conductivity (λ) varies with the core. ThicknessThe insulation thickness, not the total thickness of the panel. AreaThe total panel area covered on this surface.

Roof m²

Wall m²

Floor m²

Roof, wall and floor are entered once each. + layer is for the case where a second panel is laid over an existing one: if PIR has gone over an old rock wool panel, there are two layers on the same area, their resistances add and the U-value falls.

This value is the annual heat loss through the building envelope by conduction alone; it does not represent the total energy consumption of the building. Ventilation, air leakage, windows, thermal bridges, internal gains and solar gains are not included.

Payback on the insulation investment Shows the payback on the total investment in the insulated panels selected, against the theoretical annual energy saving compared with the uninsulated steel reference. Enter the price per m² for each surface.

RoofPIR 60 mm · 1,200 m² ₺/m² WallPIR 80 mm · 900 m² ₺/m² FloorPIR 100 mm · 600 m² ₺/m²

Panel investment—

Theoretical annual energy saving—

Payback period—

Theoretical net gain over 10 years—

Enter the panel price per m² for each surface to get the payback period. The results in this section are the output of a calculation. They are not an undertaking, a guarantee or a price quotation and cannot be used as such.

cold winter, -2 °C · Industrial building 2,700 m² of panel

67,286kWh/year

Inside 18 °C, the temperature held in winter.

141,300 ₺ The annual cost of that heat, at 2,10 ₺/kWh.

3,589 Heating degree days

Against an uninsulated reference

With an uninsulated steel envelope3,024,978 ₺

With insulation141,300 ₺

2,883,678 ₺difference in annual heat loss

This value is the difference in annual conduction heat loss between an uninsulated steel envelope and the insulated envelope selected. It is not a saving on an actual energy bill.

By surface

Roof · PIR 60 mm 36,050 kWh · 54%

Wall · PIR 80 mm 20,367 kWh · 30%

Floor · PIR 100 mm 10,868 kWh · 16%

U-values

RoofU 0.35

recommended 0.25 · 90 mm brings it below the recommendation

WallU 0.26

recommended 0.35 · this selection is below the recommendation

FloorU 0.21

recommended 0.30 · this selection is below the recommendation

The smaller U is, the smaller the loss. The criterion is the TS 825 recommendation for heated buildings.

Heat Loss Calculation

Building and climate

Climate
Building type
Internal temperature
Heating degree days

Result

67,286kWh/year

Annual cost
Gain over an uninsulated steel envelope

The annual heat loss is the heat passing by conduction through the panel-clad surfaces in a year. Its money value is found by multiplying by the unit price written at the top of the report. The gain line is the difference between the loss with the same surfaces clad in uninsulated steel and the loss with panels. The thermal transmittance of uninsulated steel is taken as U = 1 / (Rsi + Rse); the resistance of the steel itself is neglected.

Distribution of the loss across the surfaces

The percentages in the drawing show which surface the annual heat loss leaves through, and they add up to 100. Whichever surface carries the largest share, increasing the insulation thickness there gains the most.

The next page carries the panel section for each surface, the U-values and the distribution of the loss across the surfaces. The last page holds the monthly external temperatures the calculation rests on, the method, the scope and the nature of the document.

Heat Loss Calculation

Surfaces and panel sections

The drawing below shows the envelope of the building, and the sections show the panel on each surface. In a section there is a core between two steel sheets, and the dimension gives the insulation thickness, not the sheets. Where a surface has two layers, the upper one is the panel laid later over the existing one; the thermal resistances of the two layers add.

The texture in the sections shows the core: rigid foam has yellow cells, rock wool green fibres and EPS white beads. The dark bands are the steel sheets on the two faces of the panel; their thermal resistance is not included in the calculation.

U-values

The recommended values in the report are the maximum U-values given in TS 825:2024 Annex A.2 for the climate and surface selected, and they are for heated buildings. Those values are on an element basis; what binds under TS 825 is the annual heating energy calculation for the building, and a suitable result can be reached for the building as a whole while one element is above the recommendation. This table is not required for unheated warehouses, canopies, partitions and cladding. Outside Türkiye the limit values vary by country.

Annual loss surface by surface

The segments of the bar show the distribution of the annual loss across the surfaces as lengths. The figures beneath are the heat leaving each surface in a year.

Heat Loss Calculation

Monthly data

The annual loss is the sum of the monthly calculations. In months where the external temperature stays above the internal one there is no heating, and those months do not enter the total. The degree day column is the temperature difference for that month multiplied by the number of days.

Month	External temperature	Degree days
January	-3.0 °C	651
February	-2.7 °C	580
March	0.4 °C	546
April	6.4 °C	349
May	14.0 °C	124
June	18.7 °C	—

Month	External temperature	Degree days
July	28.4 °C	—
August	26.9 °C	—
September	17.2 °C	24
October	13.0 °C	155
November	-1.8 °C	594
December	-0.3 °C	567

Annual total3,589

Method of calculation

The thermal transmittance U is calculated to EN ISO 6946: R = Rsi + Σ(d/λ) + Rse and U = 1/R. The surface resistances are taken according to the direction of heat flow. The annual loss is found from Q = U × A × DD × 24 / 1000, where DD is the heating degree days, summed for every month below the internal temperature from the temperature difference multiplied by the number of days. The monthly average external temperatures are taken from TS 825:2024 Annex B.2 and the internal temperatures by building type from Annex B.1. The core thermal conductivity values (λ) are manufacturer data.

Scope and limits

The calculation covers only the heat leaving the panel-clad surfaces by conduction. Windows, doors, floor slabs, ventilation and air leakage, thermal bridges, fasteners and internal gains are not included. The thermal resistance of the steel sheets on the two faces of the panel is neglected; for 0.5 mm steel that value is 0.00001 m²K/W, and EN 14509 accepts the omission. The air gap between two layers of panel is not counted either. For these reasons the value in the report is the annual heat loss through the building envelope by conduction alone; it does not represent the total energy consumption of the building.

Nature of this document

This document is the output of a calculation. It is not a declaration of performance, a declaration of conformity or an undertaking, and cannot be used as such. The calculation has been made with the methods of the standards named above and with the values entered by the user; the suitability of those inputs for the project is the responsibility of the user. The binding values for the thermal and fire performance of the products are in the declaration of performance (DoP) and the test reports for the product. The suitability of the application for the project is assessed by the relevant engineer or architect.

Nuhpanel Yapı Elemanları A.Ş. · G.O.S.B. İhsan Dede Cd. No:111, Gebze / Kocaeli · +90 262 751 07 79 · nuhpanel.com

Method

The U-value is calculated to EN ISO 6946: R = Rsi + Σ(d/λ) + Rse, U = 1/R. The annual loss follows from the heating degree days, found for each month from the difference between the internal and external temperatures multiplied by the number of days. The monthly average external temperatures are taken from TS 825:2024 Annex B.2 and the internal temperatures from Annex B.1.

Scope

The result is the heat leaving the panel-clad surfaces by conduction. Windows, doors, floor slabs, ventilation, thermal bridges and internal gains are not included; all of those belong to the energy calculation for the building and cannot be done without looking at the project.

Criterion

The recommended values on the card come from TS 825:2024 Annex A.2 and are shown as a single line for the climate and surface selected; the whole table is not published. Those values are for heated buildings and are on an element basis: what binds is the annual heating energy calculation for the building, and a suitable result can be reached for the building as a whole while one element is above the recommendation. This table is not required for unheated warehouses, canopies, partitions and cladding. Outside Türkiye the limits vary by country; each country sets them in its own regulations, and in that case you can enter your own target.

Heat Loss and Savings

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