An open fireplace offers a direct fire experience, crackling sound and authenticity. A closed fireplace, on the other hand, delivers a much higher efficiency and seems more logical in an airtight nearly zero-energy home. In modern new build, architects often choose closed systems, unless atmosphere takes centre stage. Yet both types are technically possible today, including bespoke, in contemporary homes. This guide helps you choose on the basis of 7 concrete criteria.

In brief

• Open or closed is independent of the fuel: both exist in wood and in gas.
• An open fireplace reaches +/- 15 to 25 percent efficiency, a closed wood burning fireplace 75 to 85 percent and a closed gas fire up to +/- 90 percent.
• Closed built-in fireplaces are the logical choice when the focus is on efficiency, ease of maintenance and nearly zero-energy compatibility. Bespoke open fireplaces when the focus is on atmosphere and architectural presence.
• Even in an airtight home an open fireplace is possible, with a flue gas fan and electric dampers that only open during use.
• Since 2003 Metalfire has produced both open and closed fireplaces in wood and gas in its own workshop in Evergem, the closed lines in fixed dimensions, the open lines bespoke.

What is the difference between an open and a closed fireplace?

The biggest difference lies in the way combustion takes place. With an open fireplace, the combustion chamber is directly connected to the living space and is room-air dependent. You feel the heat directly on your skin, hear the fire crackle and experience the play of flames in a direct way. That creates an intense atmospheric experience.

A closed fireplace works room-sealed; in this design, combustion takes place behind a glass panel. The air supply and flue gas outlet are controlled, so the fire burns more efficiently.

Important: 'open' or 'closed' is independent of the fuel. Both wood and gas fireplaces exist in both designs. A bespoke open gas fire in an airtight home also remains technically possible, provided adapted engineering such as flue gas fans, flue gas detection and electric dampers.

The choice between open and closed is therefore not only emotional, but also technical and architectural. Manufacturers who design both systems can compare those differences objectively within the same range.

What efficiency does an open versus a closed fireplace deliver?

Here the closed fireplace clearly wins on efficiency. An open fireplace typically reaches an efficiency of around 15 to 25 percent, for both wood and gas. The largest part of the heat disappears directly up the chimney.

With closed systems it is completely different. A closed wood burning fireplace reaches 75 to 85 percent efficiency. Closed gas fires can even go towards 90 percent. That difference arises because the glass panel and the controlled air supply keep the heat in the combustion chamber longer.

For purely atmospheric use, efficiency often plays a smaller role. An open fireplace that burns occasionally on a winter evening is usually not chosen to save energy, but for the experience.

Metalfire publishes the efficiency figures of its models transparently (not for open appliances), so architects and clients can correctly compare different systems.

What atmosphere and experience does each type offer?

In terms of emotion and fire experience, an open fireplace remains unsurpassed for many people. The crackle of wood, the interaction with the play of flames and the direct heat radiation create a feeling strongly connected to calm and tradition. That cultural aspect often plays a bigger role than technical performance.

A closed fireplace approaches fire in a different way. The flame picture is made visible in a controlled way behind glass. Thanks to larger glass surfaces, a panoramic view of the flames arises that works particularly architecturally.

With gas too, the differences have become smaller. Modern open gas fires such as the Urban range today come surprisingly close to the natural wood-fire picture. As a result, the direct atmospheric experience is preserved, without wood storage or ash residue.

For many architects, the difference ultimately lies in the role of the fireplace in the interior. An open fireplace feels tactile and lively. A closed fireplace often works more strongly as an integrated design object with a clean play of lines.

Which type suits a nearly zero-energy or airtight home?

This is today one of the most frequently asked questions in new-build projects. Many people think an open fireplace is impossible in a nearly zero-energy home.

Modern nearly zero-energy homes are built airtight and often work with type D balanced ventilation. As a result, a fireplace must not cause uncontrolled negative pressure. A closed wood burning fireplace or a closed gas fire with a concentric flue system is therefore usually the simplest solution.

Yet an open fireplace can also be integrated into an airtight home. That does require a much more complex technical approach. With a flue gas fan, the flue gas outlet is controlled mechanically, while electric dampers only open during use of the fireplace. This keeps the home airtight when the fireplace is not active.

For bespoke projects, Metalfire works out this engineering entirely in-house in Evergem, in consultation with the dealers, architects or engineering firms.

What maintenance does each type involve?

Maintenance often plays a bigger role than people expect beforehand. An open or closed wood burning fireplace generally requires the most maintenance. The chimney must be swept one to two times a year and the ash residue must be removed regularly. With a closed wood burning fireplace, the glass must also be cleaned regularly and, after prolonged use, seals must be replaced.

Closed gas fires are the simplest to maintain. There is no ash, no wood storage and hardly any dust formation. However, an annual check by an approved installer remains important.

Open gas fires combine the maintenance advantages of gas with the extra technical control of flue gas ventilation, backdraught protection and electric dampers where these are present.

What investment does each involve?

The cost depends strongly on bespoke work, installation complexity and finish. A standard closed fireplace is usually more accessibly priced than a fully open bespoke fireplace.

In the Benelux, a closed built-in fireplace generally lies between €5,000 and €14,000 for the appliance itself. On top of that come installation costs of around €2,000 to €6,000, depending on the flue gas run, chimney situation and finish.

Bespoke open fireplaces are often in a higher price range. Not only because of the fireplace itself, but above all because of the additional engineering, ventilation solutions and technical integration in airtight homes.

The wisest advice remains to always split quotations into appliance, flue gas outlet, ventilation and finish. That way you compare different systems more fairly.

What bespoke options does each offer?

Closed fireplaces, both wood and gas, are supplied in standard dimensions from which you choose. These appliances are certified in the dimensions in which they exist, and the range of formats is wide enough to find a fitting solution in virtually every project. In addition to the width/height ratio, there is also a choice in arrangement: front models, corner fireplaces, tunnel fireplaces and three-sided versions integrate the fire into modern architecture. With premium manufacturers, glass surfaces run up to around 1.5 metres wide.

The open appliances, such as the Universal and Urban, are produced fully bespoke. That requires more technical expertise, which is why fewer manufacturers offer it. Especially in airtight homes, an open fireplace requires thorough engineering around flue gas outlet and ventilation.

The finish often determines the difference between a standard fireplace and an integrated architectural element. Metalfire finishing frames of 10 mm, for example, provide a much cleaner play of lines. Special finishes such as Maple Gold or Terracotta reinforce the character of the flame picture without being dominant.

An additional advantage of manufacturers who design both types is stylistic coherence. In projects where open and closed fireplaces are combined, materials, proportions and finishes stay consistent.

Since 2003 Metalfire has produced both open and closed fireplaces in its own workshop in Belgium, the closed lines in fixed dimensions, the open lines bespoke.

Which manufacturers make both open and closed fireplaces to bespoke order?

There are fewer than many people think. Producing a closed fireplace is technically completely different from developing a bespoke open fireplace for an airtight home. That is why many manufacturers specialise in only one system.

Yet it can be interesting to work with a manufacturer that masters both. Especially in architectural projects where different fireplace types are combined, this ensures a coherent design language and technical coordination.

Typically these are premium European manufacturers with their own engineering and production. Metalfire is an example of this. The Belgian company in Evergem has designed and produced both open and closed fireplaces in wood and gas since 2003, including bespoke solutions for nearly zero-energy homes.

Anyone having conversations with a manufacturer should explicitly ask how open fireplaces are integrated into airtight homes and what technical guidance is provided.

When do you choose which?

The right choice ultimately depends on home type, use and atmospheric expectation.

For many contemporary projects, the choice is not about 'better' or 'worse', but about priorities. Efficiency, maintenance and nearly zero-energy compatibility often point towards closed systems. Emotion, fire experience and architectural presence more often steer towards open fire.

With premium manufacturers such as Metalfire, both approaches can be worked out within the same design philosophy.

The Metalfire approach: both types in own production

Since 2003 Metalfire has designed and produced architectural fireplaces in its own workshop in Evergem. Each year around a thousand fireplaces are produced for residential projects and architectural interiors worldwide.

What makes Metalfire special within this subject is that both open and closed fireplaces are designed and produced in wood and gas. As a result, each project can be considered both technically and aesthetically from the same vision.

For airtight homes, the team develops solutions with flue gas fans, electric dampers and concentric flue systems.

Architects are often involved from the very first design phase. In the workshop in Evergem, materials, finishes and technical integrations can be reviewed in advance.

Checklist: what questions to ask when choosing?

Before you choose an open or closed fireplace, it helps to lay these seven criteria side by side:

• Do you mainly want atmospheric experience or does heat output take priority?
• Does the fireplace fit in a nearly zero-energy or airtight home?
• How important is ease of maintenance?
• Is the fireplace used decoratively or functionally?
• How important is architectural integration?
• What investment fits within the project?

Anyone still in doubt is best advised to discuss the choice early with an architect, installer or fireplace manufacturer. That way you avoid technical limitations later in the process.

Discover the different systems in our wood burning fireplaces and gas fires, visit a dealer or request technical advice at support@metalfire.eu.

About Metalfire

Since 2003 Metalfire has designed and produced bespoke fireplaces in its own workshop in Belgium. Our team of designers and engineers combines Belgian craftsmanship with technical expertise, innovation and craft.

We work on a project basis with architects on architectural interiors where fire is not an addition, but an integral part of the design. Thanks to technical guidance, detailing and bespoke solutions down to the millimetre, we support an integrated approach from design to delivery.

This page was compiled in collaboration with the Metalfire Design Team, made up of designers and engineers who develop gas and wood fireplaces every day for high-end architectural projects. Their experience in engineering, design and bespoke work guarantees the accuracy, quality and expertise on this page.