The result “Enhanced HVAC solution with integrated renewable energy and low-temperature heating” describes a …

The tool addresses the need for climate-resilient, low-carbon HVAC retrofits in existing and cultural-heritage buildings where conventional high-temperature heating systems are difficult to decarbonize and where architectural constraints limit invasive interventions. This need is especially relevant for large public buildings connected to district heating networks, such as the Riga Central Market pavilion, where future operation must handle both winter cold waves and summer heat waves while maintaining acceptable indoor comfort and reducing operational emissions.
The result responds to three practical problems. First, many heritage buildings require heating and cooling solutions that respect floor build-up limits, existing shop layouts, structural restrictions, and preservation requirements. Second, district-heated buildings often operate with temperature regimes that are not optimized for low-exergy renewable integration. Third, climate change increases the risk of comfort violations during extreme weather, so HVAC systems must support both decarbonization and resilience.

The tool is an integrated HVAC retrofit solution; it is not a standalone software tool. The solution combines five main components: building-integrated photovoltaics (BIPV), a reversible heat pump, the existing district heating network, a low-temperature substation, and a combined low-temperature heating/high-temperature cooling distribution system based on the Uponor underfloor network. In heating mode, return water from the district heating network at approximately 42-46 C feeds the low-temperature substation, where it is tempered to supply the radiant floor network. In cooling mode, the reversible heat pump supplies chilled water at approximately 16-18 C to the same distribution network, using the floor as a high-temperature radiant cooling emitter.

The integrated solution is currently available within the MULTICLIMACT project as a preliminary design for the Latvian demonstrator. A simplified replication package could also support future feasibility studies for other district-heated heritage buildings.

The main user groups are municipalities, public building owners, facility managers, district heating operators, HVAC engineers, energy consultants, architects, and heritage building managers responsible for renovation and climate adaptation.

The tool helps future users move from a general decarbonization target to an implementable HVAC retrofit concept. It shows how an existing district-heated heritage building can shift toward lower supply temperatures, higher renewable-energy use, and improved comfort resilience without relying only on conventional high-temperature emitters.

The tool is being developed for the Latvian demo site at Riga Central Market. D9.3 reports the preliminary low-temperature heating design, including circuit and manifold layout, component specifications, BOQ, and performance analysis. The design will be further tested and fine-tuned in T11.4 and T15.4.

More information you can read under Deliverable 9.3.