A window heat pump from Midea is reshaping urban heating in New York

In the depths of a hard winter, a discreet unit fitted into a window is starting to challenge traditional radiators and noisy space heaters.

New York has become a testing ground for a technology that claims it can keep flats warm even in extreme cold, using less energy and without any building work. The idea arrives as households and cities face pressure to cut electricity bills and reduce emissions - prompting a blunt question: are we looking at the next chapter of urban heating?

A heater that starts in the window, not the wall

At the centre of this shift is a window heat pump developed by the Chinese giant Midea. Unlike the inverter air conditioners many people already know, this unit was designed to fit straight into vertically sliding sash windows - common across New York, Boston and many Canadian cities.

The principle is straightforward: instead of drilling through walls, running pipework and mounting an outdoor condenser, the whole system is built into a single block that sits in the window opening. In day-to-day terms it resembles a more powerful window air conditioner, but it uses a reversible heat-pump system, so it can heat and cool.

"This heat pump operates reliably down to –22 ºC, using far less energy than conventional electric heaters."

The pitch is aimed squarely at older buildings, blocks with strict façade rules, and rented properties where even minor alterations can become a saga. Based on early tests and first-hand accounts in New York, fitting takes under an hour and can be done without a specialist engineer, provided the user is comfortable with heavy-duty DIY - the unit weighs about 59 kg.

How a single unit manages heating in extreme cold

What stands out most is its ability to keep working at temperatures where many conventional heat pumps effectively give up. Midea’s unit continues producing heat at –22 ºC outdoors and has a theoretical limit close to –25 ºC - a crucial detail for places hit by severe cold snaps.

In terms of output, heating capacity drops to roughly 1.4 kW in the harshest conditions, which is enough for a well-insulated, medium-sized room. In milder weather, with an outside temperature of 8.3 ºC, it reaches about 2.6 kW - a heating band comparable to many wall-mounted systems sold today.

The heart of the system: a compressor that never fully “switches on and off”

The key lies in a new-generation compressor that runs in a modulated way. In other words, it doesn’t behave like older systems that operate in a blunt “all or nothing” cycle - blasting at full power, overshooting the target temperature, then shutting down entirely.

With this heat pump, the compressor continually adjusts its speed to match outdoor conditions and the amount of heat the room actually needs.

"By modulating power, the system uses less, avoids peaks and delivers a more stable and comfortable thermal feel."

In practice, that means fewer sharp swings in temperature. The unit keeps the room steadily warm, rather than repeating the familiar pattern of overheating followed by cooling that is typical of simple resistive electric heaters.

Quiet, savings and space: the real-world trade-offs

Anyone who has lived with a loud portable heater or an ageing air conditioner knows noise can make a big difference to day-to-day comfort. With that in mind, Midea includes a quiet mode rated at 29 dB(A), roughly comparable to a whisper or a calm library. In normal use, noise levels sit around 51 dB(A), which is still reasonable for a living room or bedroom.

The downside of this robustness is its size and weight. At 59 kg, the block takes up a significant portion of the window opening. In smaller flats, that can mean less natural light and reduced ventilation during spring and autumn. Some residents still favour compact wall-mounted units, which sit more discreetly on an internal wall and interfere less with the exterior.

What it costs to heat without inflating the electricity bill

Upfront cost is not modest. In the United States, prices range from US$2,800 to US$3,000 per unit, before any public subsidies. The manufacturer says costs should fall as production scales, but for now the main targets are:

• building and condominium managers;
• social landlords and social housing;
• pilot programmes in cities with severe winters, such as Boston;
• energy-efficiency projects in Canada.

Even at a high ticket price, many decision-makers are thinking in long horizons: heat pumps typically deliver two to four times more heat than the electricity they consume, whereas resistive electric heaters convert roughly 1 kWh of electricity into 1 kWh of heat. In places that need fast warm-up and stay cold for many months, the cumulative difference in energy use can become decisive.

Why this innovation still cannot be installed in Brazil

For now, this window heat pump has no obvious place in most Brazilian cities - or even in large parts of mainland Europe. The barrier is more architectural than technological: the current units were designed for sash windows, the up-and-down type that slide in vertical tracks, typical of New York and also found in older homes across the United Kingdom and Canada.

In Brazil, sliding windows, tilt windows and side-hinged casements are far more common. None of these styles matches the requirements of this unit, which needs solid support along the bottom edge of the opening and a clearly defined gap that can be properly sealed.

"Without a design specifically for sliding or tilt windows, safe installation in Brazilian buildings is still not viable."

Countries where sash windows are widespread - such as Canada, the United States and the United Kingdom - are likely to be the first to establish this technology at scale. Only later would it make sense to produce a line adapted to other window standards.

What changes in the concept of urban heating

This kind of heat pump introduces a different approach to renewing a city’s heating stock. Rather than overhauling a building’s entire central system, it allows a transition flat by flat, unit by unit. Residents or social-housing managers can gradually replace gas, oil or resistive heaters with modular window units.

That creates several practical effects:

Aspect	Potential impact
Energy bill	Lower electricity consumption compared with resistive heaters, particularly with prolonged use.
Emissions	Less burning of gas or oil in individual systems, with lower CO₂ where the electricity grid mix is cleaner.
Thermal comfort	More stable temperature and better heat distribution in small and medium spaces.
Building management	Gradual rollout without costly structural refurbishments or long disruptions for building works.

Practical scenarios: from everyday residents to social-housing managers

Picture an older New York building with inefficient steam-based central heating, draughty windows and tenants topping up with portable heaters. Instead of replacing the entire boiler and pipe network, the management could fit window heat pumps in the flats most exposed to the cold, such as corner units or those on higher floors.

In a second example, a Canadian public social-housing programme chooses to focus on the energy bills faced by low-income households. Gradually swapping resistive heaters for window heat pumps could ease monthly costs and reduce reliance on fossil fuels during colder spells.

These scenarios suggest the technology speaks not only to comfort, but also to public policy, health (less mould and damp in cold homes) and even longer-term urban planning.

Terms worth knowing before discussing heat pumps

To make sense of this kind of innovation, a few concepts come up repeatedly:

• Air-to-air heat pump: a system that extracts heat from outdoor air and transfers it indoors, unlike heaters that create heat directly from electricity or by burning gas.
• Power modulation: the compressor’s ability to vary its output, avoiding on-off cycling and improving efficiency.
• Coefficient of performance (COP): the ratio between heat delivered and electricity consumed. The higher the COP, the more efficient the unit.

For people living in Brazilian regions with harsher winters - such as Serra Gaúcha or the southern part of Minas Gerais - this window heat pump may feel like a glimpse of solutions that could later be adapted to local building styles. Today, window design is the practical obstacle, but the underlying idea - heating efficiently even in intense cold - is likely to spread, including to compact wall-mounted versions and hybrids paired with solar energy.