Where does heat escape from a house?

Where does heat escape from a house: heat loss and passive house principles

In this article, we will look at what is really worth saving on when designing a private house from the point of view of energy efficiency. This is not about using cheap materials, but about making the right design decisions that help reduce heat loss for decades of building operation.

Reflections by engineer Pavlo Biriukovych on passive house design and an answer to a simple but very important question:

How much heat does a house really need?

Imagine Germany: simple houses, well-kept streets, neat facades and a rational approach to energy consumption.

When we talk about heat, a significant part of thermal energy consumption is related to the residential sector. Houses need energy for winter heating, summer cooling, ventilation and domestic hot water. That is why the energy efficiency of a private house should be considered at the design stage.

In Ukraine, the situation also shows that residential buildings have great potential for energy savings:

The conclusion is simple: the lower the heat loss of a house, the less the owner spends on heating, cooling and domestic hot water. As energy prices rise, this issue becomes even more important.

Based on our experience, many clients try to save money during construction on the very solutions that affect their expenses for decades: insulation, ventilation, airtightness, windows and efficient heating equipment. At the same time, considerable sums are often spent on finishes, furniture and accessories that do not reduce future heating bills.

A house may be used by one family for 50–80 years. During all this time, the owners pay every year for heating, cooling and hot water.

The problem of high heating costs can be solved by designing a passive or energy-efficient house. Such a house provides a comfortable indoor climate while consuming significantly less energy for heating, cooling, ventilation and domestic hot water.

How does it work?

1. Start by reducing heat loss

House shape. Heat loss through external walls, roof, attic floor, ground floor, windows and ventilation depends not only on materials, but also on the shape of the house. The more compact the building shape, the smaller the area of the external envelope and the easier it is to reduce heat loss.

The most compact geometric shape is a sphere, but living in a sphere is not practical. For real construction, a simple rectangular or square plan without unnecessary projections, bay windows and complex roof shapes is close to a compact form. That is why a simple house shape is often an advantage for an energy-efficient or passive house.

Insulation. In addition to the shape of the house, thermal insulation plays a key role. First of all, the roof or attic floor should be properly insulated, followed by the external walls, ground floor or floor above the basement. Together, these elements form the thermal envelope of the house.

Windows. A house also loses heat through windows. Energy-efficient window profiles, warm edge spacers and high-quality glazing units help significantly reduce these losses. It is also important to orient windows correctly according to the cardinal directions and provide protection from overheating in summer.

Read more about choosing warm windows in our article =>

Additional heat loss through windows can be reduced by using external shutters, blinds or other heat-protection solutions.

Ventilation. A significant part of heat can be lost through uncontrolled air exchange. If a house does not have a properly designed ventilation system, warm air escapes outside and cold air enters the rooms without preheating. Mechanical ventilation with heat recovery provides fresh air while reducing energy losses.

2. Use free solar energy

Almost every room in a private house has windows. Through them, a house can not only lose heat, but also receive useful solar heat gains. To make use of this, it is important to properly plan the southern facade, window placement and room layout.

Windows on the south-facing facade can help heat the house in winter. On the northern side, where there is almost no useful solar heat, the glazing area should usually be limited. At the same time, summer overheating must not be ignored: large windows without sun protection can increase the load on the cooling system.

3. Do not forget building physics

There is a common opinion that a “good” wall should breathe. In reality, this is a dangerous simplification. During the use of a house, moisture is constantly produced indoors: from people breathing, cooking, showering, washing and other everyday activities.

If this moisture enters the building envelope and accumulates in the insulation or wall structure, the thermal performance of the construction deteriorates. That is why airtightness, correct vapor control, the absence of thermal bridges and well-designed ventilation are essential for an energy-efficient house.

High-quality vapor control and an airtight envelope are among the key principles of a passive house. Excess moisture should be removed not by “breathing walls”, but by a properly designed ventilation system.

4. Use modern engineering systems

A modern heating system should be not only powerful, but also flexible, controllable and economical. It is good when the system can use several energy sources and operate in an optimal mode.

For example:

• gas boiler + solid fuel boiler + solar thermal system;
• solid fuel boiler + heat pump + solar thermal system;
• heat pump + ventilation system with heat recovery + solar panels.

It is important to be able to control the temperature in each room separately. This helps avoid overheating rooms that are not used temporarily.

Programmable thermostats and weather-compensated heating control have proven to be effective. They make it possible to lower the temperature in the house when nobody is at home and return it to a comfortable level before the residents come back.

Additional solutions can also help save resources: using rainwater for irrigation, reusing technical water where possible, energy-efficient lighting and properly configured automation.

5. Approach construction carefully

Even a good design can be spoiled by poor workmanship. Every careless detail reduces the result: poorly installed insulation, breaks in vapor control layers, unsealed joints, thermal bridges, mistakes in window installation or ventilation systems.

That is why for a passive or energy-efficient house, correct calculations are not enough. Careful construction, design supervision and quality control of the work are equally important.

What result can be achieved?

Practice shows that an energy-efficient or passive house may require several times less energy for heating than a conventional house of the same size. The final result depends on architecture, insulation, windows, ventilation, airtightness, engineering systems and construction quality.

Older calculations often used examples of gas consumption for a passive house of about 150 m². Such figures may be useful as a historical reference, but today it is more correct to evaluate the economics using current tariffs, the heat loss of a specific house and the actual heating system.

Passive house and ordinary energy-efficient house: what is the difference?

For comparison: in many houses in Ukraine, even after insulation, significant heat losses may remain due to thermal bridges, insufficient roof insulation, weak windows, inefficient ventilation or installation mistakes.

This is why formal “insulation” does not necessarily mean that a house has become truly energy-efficient. It is important to assess the entire system: architecture, structures, windows, ventilation, heating, airtightness and construction quality.

If everything is designed and built correctly, the energy consumption of a house can be significantly reduced without losing comfort.

In Germany, passive houses have long been built not as single experiments, but as entire streets and neighborhoods. This shows that energy-efficient construction can become not an exception, but a normal approach to residential design.

A short note:

In European Union countries, building energy efficiency requirements are gradually becoming stricter. New houses are expected to consume less energy, and part of the energy should come from renewable sources. That is why the design of energy-efficient and passive houses is becoming increasingly important.

For Ukraine, this is also important, because reducing heat loss in private houses helps lower heating costs, improve comfort and reduce dependence on energy sources.

Contact us if you are planning to build an energy-efficient or passive house. We will help you choose the right design solutions, calculate heat loss, and plan the ventilation, heating and building structures.

Read more about what a passive house is in this article -> HERE

Call us, and together we will determine what kind of house will be optimal for you.

All articles about passive houses can be read HERE