Energy-Efficient Home

This is one of the most important indicators, showing how much energy a building consumes per square metre per year.

This indicator describes the amount of energy required for space heating. Lower consumption indicates more effective thermal insulation and a more efficient heating system.

It shows the amount of carbon dioxide emissions generated by the building, which is directly related to the energy consumed and the way it is produced.

This is a class specified in the energy certificate (usually a scale from A to G) to clearly compare the efficiency of different buildings.

This indicator includes not only the energy consumed directly in the building, but also the losses incurred during energy generation and supply.

This includes temperature, air humidity levels and ventilation quality directly affecting housemates’ well-being and quality of life.

Indicates what proportion of the total energy used comes from renewable resources, for example solar panels or heat pumps.

Heat loss most often occurs through parts of the building that are in direct contact with the outdoor environment or unheated spaces.

These are usually the following areas:

• Roof
• External walls
• Windows and doors
• Floors (located above an unheated basement or on the ground)
• Chimneys and ventilation openings
• Poorly constructed joints (for example, between a window and a wall)

Cold bridges (or thermal bridges) are areas in building structures where heat escapes significantly faster than through the surrounding surfaces. They not only reduce the effectiveness of thermal insulation and create cold surfaces in the home, but also result in condensation followed by mould growth.

If warm and humid indoor air enters the building structures and cools there, condensation forms. This can reduce the effectiveness of insulation, result in mould growth and, over time, cause serious structural damage.

Regular airing of rooms, an effective ventilation system and properly constructed structures with appropriate air and vapour barriers reduce the risk of condensation.

The building’s airtightness can be accurately checked with a “Blower Door” test. During the test, a pressure difference is created in the building using a special fan, which allows areas to be identified where air enters or escapes uncontrollably through the structures. The test identifies areas of heat loss, assesses construction quality and finds ways to reduce energy consumption.

Signs that may indicate airtightness problems:

• Noticeable draughts indoors
• Uneven temperatures in different parts of the home
• Increased heating costs
• Cold surfaces near walls, windows or doors
• Condensation forming on windows
• The appearance of mould

Ventilation systems can operate in different ways, and each solution has its own advantages and limitations. The choice depends on the type of building, its airtightness, the housemates’ habits and comfort requirements.

• Natural Ventilation. Air exchange takes place naturally through ventilation ducts and pressure differences. The system does not consume electricity, while its efficiency varies and depends on weather conditions.
• Mechanical Ventilation. Air exchange is ensured by a ventilation unit that controls the supply of fresh air and the extraction of waste air. It ensures stable air quality regardless of external conditions.
• Ventilation with Heat Recovery. Mechanical ventilation with heat recovery. The system uses the energy of the outgoing (warm) air to heat the incoming (cold) air. This allows heat loss and heating costs to be significantly reduced while maintaining excellent air quality.

A good and healthy indoor environment is characterised by three main indicators that should ideally be maintained on a daily basis:

• Temperature from 18 °C to 22 °C – ensures comfort and good sleep (it may be cooler in the bedroom).
• Relative humidity from 40 % to 60 % – prevents dry air (respiratory irritation) and the mould growth.
• CO₂ concentration < 1000 ppm – fresh air prevents fatigue and headaches.

Recommendations for Maintaining Good Air Quality

Good air quality can be ensured by combining proper daily habits with suitable technical solutions.

• Ventilate the rooms regularly (at least 2 to 3 times a day by opening the window fully for a few minutes).
• Do not cover ventilation grilles, ducts or air supply openings.
• After cooking or using the shower, ensure additional ventilation.
• Keep the ventilation system clean and replace the filters regularly.
• The installation of a mechanical ventilation or heat recovery system shall be considered if elevated humidity or stuffy air persists in the rooms for a longer period.

The following symptoms and signs may indicate insufficient ventilation or an unhealthy microclimate in the home:

• Condensation on windows
• Mould
• Stuffy air
• Lingering odours
• Fatigue or drowsiness (especially in rooms where housemates stay longer)

To choose truly energy-efficient windows, it is important to pay attention to the following parameters before purchasing them:

• Thermal insulation performance (the lower the heat transfer coefficient U, the better)
• Air permeability class (indicates the window’s airtightness)
• Sound insulation properties (especially if the home is located close to a street)
• Security and burglar resistance class
• The quality of installation materials and workmanship
• The quality and durability of the seals

Window Orientation According to Cardinal Directions

The placement of windows in the house is also of strategic importance. Properly oriented windows (for example, facing south) help to make the most of free solar heat in winter. To reduce the risk of rooms overheating in summer, it is recommended that these windows be fitted with external shading solutions, for example blinds or solar control films.

Even the highest-quality windows and doors can lose their airtightness over time. To determine whether heat is escaping through your windows and doors, see the section “How to reduce heat consumption”, which describes simple ways to identify areas of heat loss in the home.

 It is recommended that the following actions be carried out at least once a year:

• Check the condition and elasticity of the seals.
• Lubricate hinges and other moving parts.
• Assess the overall condition of the windows and doors (for any cracks or deformation).
• Adjust the fittings if necessary.
• Regular maintenance and the timely replacement of worn elements preserve the energy efficiency of windows and doors in the long term, improve comfort and maintain an optimal indoor climate.

When choosing a light bulb, it is important to understand its parameters – not only its wattage, but also the quality of light.

 Main parameters:

1. Energy efficiency class. A – the most efficient, G – the least efficient. Indicates consumption and longevity.
2. Luminous flux (lumens, lm). The more lumens, the brighter the light. Replaces the old "watts = brightness" way of thinking.
3. Power (W). Indicates consumption, not brightness. Should be assessed together with lumens.
4. Colour temperature (Kelvin, K). Warm, cosy light from 2700 K to 3000 K; neutral white light from 3200 K to 4000 K; cool, concentration-enhancing light from 4000+ K.
5. Colour rendering (Ra). The closer to 100, the more natural the colours appear.

Smart devices are suitable if individual, simple improvements are needed in an existing home. A building management system (BMS), meanwhile, is a unified, comprehensive solution that is usually planned for new builds or large-scale renovation projects.

• Smart devices – easy to install and take the first step towards modernisation of your home.
• Building management system – ensures centralised control of all systems and broader integration options.

Which Solution should You Choose?

• If the goal is to gradually improve home comfort and reduce energy consumption with small investments, the smart devices will be more suitable choice.
• If unified and efficient management of the entire building with a high level of automation is required, the building management system will the right choice.

Smart devices are separate, autonomous technological solutions easy to install and use on a daily basis. Usually controlled via mobile apps or voice assistants, they are ideally suited to the gradual modernisation of your home.

• Lighting – smart bulbs
• Climate control – smart thermostats
• Power supply – smart sockets
• Security – security cameras and sensors
• Household appliances – smart refrigerators, washing machines, etc.

Advantages: Relatively low initial costs and very simple installation. Efficient control of specific functions (for example, lighting or heating), resulting in reduced energy consumption.

Disadvantage: As the devices from different manufacturers often operate on different platforms, their integration and centralised control may be limited or complex.

A Building Management System is a centralised platform that combines several technical systems of a home or building within a single network. It provides the coordinated control of heating, ventilation, lighting, security systems, electricity consumption and other functions.

• Centralised control – all systems managed from a single point.
• High level of automation – availability of automated scenarios (for example, "leaving home" and "returning home").
• Efficient management – detailed data analysis leads to optimised resource consumption and costs reduction.
• Extensive possibilities – unlimited possibilities for enhancement and customisation in the future.

Such systems are particularly suitable for larger private houses, apartment buildings or commercial properties with complex infrastructure management required. Implementing the BMS usually requires a higher initial investment, as well as professional planning and installation, therefore it is most often integrated at the construction stage.