The Energy-Efficient Buildings of the Future Don’t Need Circulation Pipes (VVC)

By Tamina Thamsborg, Nordnest

Energy losses in today’s buildings are often hidden in the plumbing – especially in circulation systems that constantly waste heat.

Nordnest’s EkoNod installation and bathroom modules offer a smarter alternative by integrating heating and hot water solutions directly within each apartment from day one. The concept is already being implemented in several ongoing projects.

Why this matters

New apartment buildings today are designed to meet strict energy performance requirements.
Yet measurements repeatedly show that actual energy use is significantly higher than predicted.
One of the biggest sources of energy loss hides in the invisible – the plumbing, especially for circulation (VVC) and heating systems.

A feasibility study from BEBO revealed that heat losses from hot water and circulation can be almost ten times higher than the figures used for building permits.
In one student housing project, measured losses reached 28 kWh/m² per year, even though the energy model predicted only 3 kWh/m².
The difference came down to the length and design of the pipe runs.

Energy losses built into the floor plan

The problem often begins at the drawing board.
When the architectural layout is completed first, technical systems are forced to adapt afterward.
The result: long pipe runs beneath the foundation, extra shafts, and tight spaces that amplify heat losses.

“It’s well known that shorter pipes mean lower losses, but in reality, technology often has to compromise with architecture. That’s when the energy gap is built into the house itself,” says Edwin Måradson, Co-founder of Nordnest.

Beyond unnecessary energy use, this also poses risks to indoor water quality.
Shafts where hot water loses heat can reach over 25°C – enough to warm nearby cold-water pipes.
That raises the risk of Legionella, something the Swedish Building Code warns against and even sets temperature limits for after eight hours of stagnation.

VVC – an invisible energy thief

Traditional plumbing systems circulate hot water continuously throughout the building to ensure it reaches the tap within about ten seconds.
But this “VVC” solution comes at a high cost: the system can account for up to 30% of total heat losses in a multi-residential building.
It also drives up return temperatures in district heating systems and increases the need for peak-load heating in heat pumps.

A smarter path: EkoNod

Nordnest has developed EkoNod, a system platform that integrates installations directly within each apartment and into the construction process from day one.
Instead of circulating hot water throughout the building all year, only the heating water required for space heating is distributed vertically — and that heat is then used to produce domestic hot water locally within each apartment.
In other words: five pipes become three (heating supply, return, and cold water).

Each apartment has its own secondary heat exchanger unit, where water is heated locally, eliminating the need for circulation.
The result is up to 30% lower heat losses, shorter pipe runs, no Legionella risk and significantly higher operational reliability.
Any leaks or faults are limited to a single unit rather than the entire building.
Heat for space heating is also exchanged locally, enabling individual metering and billing if desired.

Prefabrication as quality assurance

EkoNod modules are delivered as prefabricated smart bathrooms that include all the apartment’s intelligence and installation technology.
Only minimal work is required on site — and what little is needed can be done by a single installer, instead of the usual three to four trades.
This makes on-site installation faster, more precise, and far less prone to quality issues.
EkoNod is a fully engineered, optimized, and moisture-secure turnkey solution.

To further enhance energy performance and reduce both energy and peak-load costs, EkoNod can also recover heat from shower water – turning every shower into a small source of energy for the system.

Conclusion: Rethink, redesign, and integrate technology from the start

Shorter pipes are important – but they’re not the whole answer.
To truly close the energy gap, technical systems and architecture must evolve together.
With a platform like EkoNod, buildings can finally meet their designed energy performance — not just on paper, but in real life.
Construction time is shortened, and unnecessary after-market costs can instead create value within the project.

”We need to move from firefighting to systematic thinking. It’s not enough to just insulate better or reroute pipes after the fact. We have to eliminate energy waste through new, innovative system solutions,” says Edwin Måradson.