How does a heat pump's performance change with fluctuating outdoor temperatures?

A heat pump's performance is critically influenced by outdoor temperatures, particularly during extreme conditions. As outdoor temperatures drop, the heat pump has to work harder to extract heat from the air or ground, which can lead to a reduction in its efficiency and heating capacity. This is because the temperature difference between the heat source and the indoor environment becomes more pronounced, making it more difficult to transfer heat effectively.

In extremely cold conditions, it may reach a point where the heat pump cannot extract enough heat to meet the heating demands of the building, leading to diminished performance. This is why choosing a heat pump rated for cold climates or supplemental heating is vital in regions with severe winters. The negative impact on performance at extreme low temperatures contrasts with the behavior in milder conditions, where heat pumps can operate more efficiently.

While the other options might imply a consistent or beneficial performance, they do not accurately reflect the challenges a heat pump faces in fluctuating outdoor temperatures, particularly at the extremes.