Definition: What exactly does smart building technology include?

Smart building technology (also known as Smart Building or Smart Home) refers to the electronically networked control of all technical trades of a property via a central platform. The systems range from simple radio solutions to KNX-based bus systems that are integrated into the electrical installation and make the property technically future-proof for 15–20 years.

• Heating & Climate — Room-specific control, heat pump control
• Lighting — Presence, daylight and scene control
• Shading — Blinds, shutters, awnings weather-dependent
• Security — Access, alarm, video surveillance, water detectors
• Energy — PV, storage, wallbox, load management
• Comfort — Multimedia, voice control, scenes

For investors: Smart home components are not just a comfort investment, but directly affect the energy efficiency class, rentability and thus the market value. Anyone acquiring a property should include the Rating of the technology in the property valuation logic.

Investment costs: What does a smart home upgrade really cost?

The cost spread is enormous — and this is exactly where the leverage lies. A retrofitted radio solution in an 80-m² apartment starts at 2,500 €, while a fully integrated KNX system in a new-build villa can exceed 80,000 €. For the investment calculation, the additional cost per m² that you have to add to the purchase price or construction costs is relevant.

Before every decision, it’s worth looking at the calculate purchase ancillary costs section, because smart retrofits are already recognized as value-enhancing in many bank loan approvals today — which positively influences your calculate equity requirement value.

Return calculation: Three scenarios for investors

What matters is not the premium, but what it brings you. We compare a classic apartment building (8 apartments, 600 m² living space, purchase price 1.8 million €) without, with comfort and with premium smart home equipment.

The gross yield only shifts marginally — the real lever is in the value increase and the security of rental income. Detailed calculations are provided by the Calculate Gross Yield calculator; for a reliable current view, I also recommend using the Cash Flow Calculator, which realistically reflects amortization, interest and management costs.

Tax Treatment: Depreciation, Maintenance Costs or Construction Costs?

This is where it gets legally tricky for rental investors — the classification determines whether you can deduct your smart home investment immediately or over 50 years. The tax office strictly distinguishes between three categories, regulated in § 6 EStG, § 7 EStG (depreciation) and § 255 HGB:

• Maintenance costs (§ 21 EStG) — fully deductible immediately
• Purchase-related expenses (§ 6 Abs. 1 No. 1a EStG) — depreciated over time if more than 15 % of the purchase price within 3 years
• Construction costs — standard depreciation → 2 % or 3 %
• Movable assets (§ 7 EStG) — own useful life, often 5–10 years

Concretely, this means: If you replace only one heating thermostat with a smart model, it is considered maintenance cost. However, if you install a fully networked KNX system with new wiring as part of a renovation within the first three years after purchase, you will regularly fall below the 15% threshold of the acquisition-related costs — and must amortize the remaining useful life. As described in the guide Real Estate as an Investment, you should consciously schedule the renovation phase for the fourth year after purchase to ensure the full tax effect.

Funding: How banks assess smart real estate

Since the EU Taxonomy and the tightening of the KfW funding framework in 2023/2024, efficiency criteria are directly included in the lending decision. Anyone presenting a property with energy efficiency class A or B — which is realistically achievable with intelligent building technology — receives interest rate reductions of 0.10–0.30 percentage points compared to class D properties at many banks.

With a loan of 1.5 million € and a repayment period of 20 years, the interest savings alone amount to 30,000–90,000 €. In addition, KfW repayment grants of up to 45,000 € per residential unit (Program 261/262) apply. The aspect of mortgage repayment planning thus gains an additional dimension. Anyone who is setting up real estate financing anyway should integrate the smart home portion from the beginning into the collateral documents.

Capital gains tax & exit: Smart technology when selling

When selling within the ten-year speculation period (§ 23 EStG), the smart home investments are counted as value-enhancing in the acquisition/production cost block. This reduces the taxable gain on disposal. Example: You have invested 35,000 € in premium technology and sell after eight years with a book profit of 280,000 €. With a personal tax rate of 42%, the allocation reduces your tax burden by around 14,700 €.

Before each exit, it’s worth checking the speculation tax calculator as well as comparing valuation methods — a modern smart building is systematically valued higher using the income capitalization approach than with the classical asset-based valuation method, because the sustainable rental income increases the multiplier.

Decision aid: Is smart technology worth it for your investment?

The honest answer is: not always. The following heuristic has proven itself in practice and replaces a formal decision tree:

• Location A+ (Munich, Hamburg) — Premium upgrade is almost always worthwhile
• Location B (medium-sized cities) — Comfort level is usually optimal
• Location C (periphery) — only basic smart, otherwise overinvestment
• Holding period < 5 years — only maintenance measures
• Holding period > 10 years — full KNX upgrade economically sensible
• New construction — always plan for smart-ready wiring

For the initial investment in this field, I recommend fully equipping a single property — ideally the pilot project — and measuring the results over two rental cycles. Those investing for the first time will find concrete step-by-step guidance in our guide to buying your first property. Those looking to scale should take the leap to buying an apartment building — there, the smart-building leverage per invested euro is the greatest.

FAQ — Frequently asked questions from investors

How does intelligent building technology affect the market value?

Current market analyses show premiums of 5–12 % compared to similar properties without smart fittings, up to 15 % in premium locations. However, the quality of integration is crucial: an outdated island solution system can even reduce value, as buyers may factor in a potential dismantling. Therefore, invest in open, standardized systems such as KNX, Matter or ZigBee 3.0, which will still be supported in ten years’ time.

Can I pass on Smart-Home costs as a landlord?

Pure investment costs are not passable on to tenants, but ongoing maintenance and service costs of the system according to § 2 BetrKV can be, provided this is explicitly regulated in the rental agreement. Modernizations according to § 559 BGB also allow for a rent increase of 8 % of the costs incurred per year — for a 20,000 € Smart-Home investment this would be 1,600 € annually, distributed across the affected residential units. This must be formally announced and justified.

Which Smart-Home investment is the biggest return driver?

From an investor’s perspective, clearly the combination of individual room heating control, photovoltaics with battery storage, and intelligent wallbox. This combination reduces additional costs by 25–40 %, qualifies for KfW funding, and often moves the energy efficiency class up by two levels. The payback period typically lies between six and nine years at current energy prices — with a remaining useful life of the technology of 15–20 years, this is clearly a positive business.

Back to the Wiki: Real Estate Lexicon

Alarm system at a glance: Protection for your property

• Securing properties, condominiums and houses from burglary and theft
• Mostly in high-quality private, business and commercial properties
• Audible alarm as a deterrent
• Modern systems with direct connection to the police as well as notification function and image recording
• More expensive systems also support through iris scanner and fingerprint recognition

Back to the wiki: Real Estate

Smart Home – Control your home directly from your smartphone

The three most important aspects that unite a smart home are comfort, energy saving and security. In these three areas, the systems should support us and stand by our side. For this, however, not much technology is needed, as one or the other might think at first, because smart homes can be set up quite easily and they include already known things, such as wireless sockets, smoke detectors or dimmers. The only new thing is that all these things are networked with each other and with the smartphone or tablet and can therefore be controlled. For example, a smart home system makes it possible for the dishwasher to stay in contact with the smartphone via radio and send a message as soon as the dishes are clean.

More comfort – this is how intelligent houses work

Smart home systems include a number of components. These include wireless sockets, window sensors, smoke detectors, LED lights or dimmers. These are controlled via a central unit and are also networked with each other. Time control and individual scenarios are made possible via WLAN.

So it is not only possible to control your house from the comfort of your sofa and, for example, to turn up the heating when your feet get cold or to lower the shutters when the TV is switched on, but it is also possible to adjust your house to time sequences. The individual lighting mood can be determined automatically according to the time of day and the incidence of light, or the front door or the garage door can be opened when you come home from work and drive up in your car. It gets even more exciting when the individual systems are linked together and run via software. This way, the house not only thinks with you, but even ahead of you. On a hot summer day, the awning is extended thanks to the heat sensor, the lawn sprinkler is started and the air conditioning in the house ensures a pleasant temperature for you. So your comfort is increased enormously by a smart home and you enjoy in their own four walls as many conveniences as never before.

The installation – how your house changes with Smart Home

Anyone who is now worried about large costs, conversion measures or the like should be warned, because this is no longer necessary. A few years ago, a smart home was only possible in new buildings or with large conversion measures in old buildings. Cables had to be laid and prices quickly reached several thousand euros. Today, smart homes are fortunately very easy to install, even in rented apartments. This is made possible by the current module solutions, which connect by radio in the close range or via the power grid as a data line over distance and make their home quite uncomplicated Intelligenter. However, you do not have to purchase the complete package directly. For those who want to start slowly, there are starter packages that are tailored to different areas. Whether wireless sockets and LED lights to be able to control the light via app or wireless thermostats and window sensors to regulate the heating in an energy-saving way. If you are convinced by the system, you can easily expand the starter sets and make your home smart bit by bit.

Saving energy – how to go green with smart home

Energy saving is one of the most important aspects of the smart home, besides comfort. So you can inform yourself about the power consumption of all devices in the house via your smartphone and also switch them ON and OFF. If you have a solar system on your roof, you can even get information about the energy produced. So with just one tap, you can turn off all appliances when you leave the house, or just the ones that use the most energy. After all, the best way to save energy is to turn off appliances that don’t use energy unnecessarily while you’re not even in the house. But this is not the only way to save energy; you can also regulate gas consumption via heating controls. Wireless sensors on windows register when and how they are opened, forward the information directly to the control centre and the software automatically regulates that the heating thermostats go down. The heat does not escape to the outside and energy is not wasted unnecessarily. This is also handy if you forget to switch off appliances or turn down the heating before you go on holiday. You can easily do this via your smartphone and save energy.

Advantages & disadvantages – Smart Home in the test

Of course, a smart home also has advantages and disadvantages. Making your home a smart home is a decision that should be well thought out, because such an intelligent house is far from being for everyone. You have to completely change your habits and get used to the new way of living.

Advantages of a smart home – comfort, energy efficiency, security

The advantages of comfort and energy efficiency have probably already become very clear, but there is another aspect that forms a major advantage of smart homes. The security. Because a smart home can make your home safer. Whether it is playing through various lighting scenarios in holiday mode or a WLAN connected camera at the front door can detect a break-in. The smart home provides security and can even protect against fire or water damage. Thanks to the wireless connection, you can switch off the forgotten iron or the cooker while you are on the move, but water detectors can also detect a burst water hose, even if the water level is only 1.5 millimetres. You will immediately receive a message on your mobile phone and can react immediately and prevent worse damage. Investing in a smart home can not only protect you and your home, but also your wallet.

Disadvantages of a smart home – committed to one manufacturer

However, the systems of the intelligent house still have one disadvantage today. The individual systems of different manufacturers are not compatible with each other. This is mainly because the manufacturers use different transmission paths. Some rely on Bluetooth, others on land and still others use power lines. So it’s no wonder that the systems can’t cooperate with each other. Fortunately, more and more manufacturers see the need to make their devices more compatible and are therefore working together. So there is a ray of hope in sight to finally eliminate the last flaw of smart homes.