Poland's technical building conditions (Warunki Techniczne, or WT) set minimum standards for the thermal performance of building envelopes, including windows. The regulations have been tightened in stages, with the most recent significant change taking effect on 1 January 2021. That update brought window requirements into closer alignment with the EU Energy Performance of Buildings Directive (EPBD) and set the groundwork for the nearly-zero energy building (NZEB) standard that applies to all new buildings in Poland since the end of 2020.

The regulatory framework

The base regulation is Rozporządzenie Ministra Infrastruktury z dnia 12 kwietnia 2002 r. w sprawie warunków technicznych, jakim powinny odpowiadać budynki i ich usytuowanie (Dz.U. 2002 nr 75 poz. 690). It has been amended multiple times. The 2013 amendment introduced a phased tightening schedule for maximum U-values, bringing milestones in 2017 and 2021.

The regulation covers all building types. Different maximum Umax values apply to residential buildings, public buildings with low energy consumption, and other categories. The figures cited below refer to windows in residential buildings (budynki mieszkalne).

Thermal insulation installed in a building wall cavity, showing layers of mineral wool between structural elements

Thermal insulation installation in a building envelope. Comparable principles apply to the frame edges of window installations. Source: Wikimedia Commons, CC BY-SA.

Maximum U-value progression for windows

The phased schedule for windows (Uw,max) in residential buildings ran as follows:

Period Uw,max (W/m²K) Notes
Before 1 January 2014 1.8 Baseline before phased tightening
1 Jan 2014 – 31 Dec 2016 1.3 First tightening step
1 Jan 2017 – 31 Dec 2020 1.1 Second tightening step
From 1 January 2021 0.9 Current requirement (WT 2021)

The Uw limit applies to the whole window including the frame. The centre-of-glass Ug value shown on glazing unit data sheets is typically lower and does not directly demonstrate compliance. A window certificate must report Uw calculated according to EN ISO 10077-1 for the specific frame and glazing combination.

Roof windows and skylights

A separate maximum applies to roof windows (okna połaciowe) and skylights. From 1 January 2021, the limit is Uw,max = 1.1 W/m²K for roof windows in residential buildings. This is higher than for vertical windows, reflecting the structural constraints of sloping and flat roof applications and the limited product range available in low-U configurations.

How compliance is demonstrated

During the building permit and construction completion process in Poland, window specifications must appear in the architectural drawings and the energy performance certificate (świadectwo charakterystyki energetycznej, or ŚCE) calculation. The ŚCE is required for all new buildings and for buildings undergoing major renovation.

Individual windows must have a declaration of performance (DoP) under EN 14351-1, which includes the CE mark and the declared Uw value. The DoP must reference the specific test or calculation method used (typically EN ISO 10077-1 for calculated values). Installers and contractors on larger projects may request manufacturer-issued product passports or technical approval documents (Aprobata Techniczna or European Technical Assessment) to support quality control documentation.

Renovation and the Czyste Powietrze programme

For existing buildings undergoing window replacement rather than new construction, Polish building law does not always require a building permit, depending on the scope of work. However, the NFOŚiGW's Czyste Powietrze subsidy programme, which funds thermal modernisation in single-family buildings, sets its own eligibility thresholds. As of the current programme rules, window replacement grants require Uw ≤ 0.9 W/m²K. This effectively aligns the subsidy threshold with the WT 2021 new-build requirement.

More information on the Czyste Powietrze programme is available directly from the NFOŚiGW website. Grant rates and eligibility conditions are updated periodically.

Cavity wall insulation installation showing insulation being injected into the wall cavity through drilled holes

Cavity wall insulation installation. Thermal bridges at window reveals are a separate consideration in whole-building energy calculations. Source: Wikimedia Commons, CC BY-SA.

The EU EPBD context

Poland's WT 2021 changes were partly driven by the requirements of the EU Energy Performance of Buildings Directive (EPBD, 2010/31/EU and its 2018 recast, 2018/844/EU). The EPBD required all EU member states to ensure that new buildings meet an NZEB standard from 31 December 2020. Poland's WT 2021 provisions form part of the national NZEB definition, which also covers overall primary energy consumption, not just individual component U-values.

The EPBD recast also introduced mandatory renovation passports and long-term renovation strategies. Poland submitted its long-term renovation strategy to the European Commission; it is publicly available and includes projections for the residential building stock based on current U-value levels in the existing housing inventory.

Thermal bridges and window installation

The way a window is installed within a wall section affects the overall heat loss of the opening, independently of the window's own Uw value. Installing the window frame at the insulation plane (warm installation) rather than at the outer face of the structural wall (cold installation) reduces the linear thermal bridge at the reveal. Polish passive house guidelines recommend positioning the frame so that the outer face of the glazing unit is flush with or within the external insulation layer.

The Psi (Ψ) value for the window-to-wall junction is calculated according to EN ISO 10211 and EN ISO 10077-2. In standard building energy calculations under the WT framework, default psi values from the national annex or manufacturer data may be used if detailed calculation is not available.

Further regulatory reference