While inflation has moderated in 2024, the consumer price index was at significantly elevated levels for most of the year. Federal policies, volatile commodity prices and geopolitical conflicts may have exacerbated, and may continue to exacerbate, increases in the consumer price index.
A sustained or further increase in inflation could have an adverse impact on our operating expenses incurred in connection with, among others, the property-related contracted services such as repairs and maintenance, janitorial, utilities, security, and insurance. Our operating expenses, with the exception of ground lease rental expenses, may be recoverable through our lease arrangements. In general, the office and life science properties are leased to tenants on a triple net, modified net, full service gross, or modified gross basis. Under a triple net lease, the tenants pay their proportionate share of real estate taxes, operating costs, and utility costs. A modified net lease is similar to a triple net lease, except the tenants are obligated to pay their proportionate share of certain operating expenses directly to the service provider. Under a full service gross lease, we are obligated to pay the tenant's proportionate share of real estate taxes, insurance, and operating expenses up to the amount incurred during the "base year," which is typically the tenant's first year of occupancy. The tenant pays its proportionate share of increases in expenses above the base year. A modified gross lease is similar to a full service gross lease, except tenants are obligated to pay their proportionate share of certain operating expenses, usually electricity, directly to the service provider. At December 31, 2024, 46% of our properties were leased to tenants on a triple net basis, 27% were leased to tenants on a modified gross basis, 21% of our properties were leased to tenants on a full service gross basis, and 6% of our properties were leased to tenants on a modified net basis, in each case as a percentage of our annualized base rental revenue.
During inflationary periods, we expect to recover some increases in operating expenses from our tenants through our existing lease structures. As a result, we do not believe that inflation would result in a material adverse effect on our net operating income and operating cash flows at the property level. However, there can be no assurance that our tenants would be able to absorb these expense increases and be able to continue to pay us their portion of operating expenses, capital expenditures, and rent. Also, due to rising costs, our tenants may be unable to continue operating their businesses altogether. Alternatively, our tenants may decide to relocate to areas with lower rent and operating expenses where we may not currently own properties, and our tenants may cease to lease properties from us. Such adverse impacts on our tenants may cause increased vacancies, which may add pressure to lower rents and increase our expenditures for re-leasing. If we are unable to retain our tenants or withstand increases in operating expenses, capital expenditures, and leasing costs, we may be unable to meet our financial expectations, which may adversely affect our business, financial condition, results of operations, cash flows, liquidity, and ability to satisfy our debt service obligations, and to pay dividends and distributions to security holders.
Our general and administrative expenses consist primarily of compensation costs, technology services, and professional service fees. Rising inflation rates may require us to provide compensation increases beyond historical annual increases, which may increase our compensation costs. Similarly, technology services and professional service fees are also subject to the impact of inflation and expected to increase proportionately with increasing market prices for such services. Consequently, inflation may increase our general and administrative expenses over time and may adversely impact our results of operations and cash flows.
Our exposure to increases in interest rates in the short term is limited to our variable-rate borrowings, which consist of borrowings under our unsecured revolving credit facility and unsecured term loan facility. As of December 31, 2024, we had no borrowings under our unsecured revolving credit facility and $200.0 million outstanding under our unsecured term loan facility. However, the increases in long-term interest rates has recently and may continue to increase our financing costs over time, as we incur new debt or refinance existing debt. Increases in interest rates increase our interest costs, which reduce our cash flows and impact our ability to make distributions to stockholders. For more information, see "Item 1A. Risk Factors-Risks Related to our Indebtedness-An increase in interest rates would increase our interest costs on variable rate debt and new debt and could adversely affect our ability to refinance existing debt, conduct development, redevelopment and acquisition activity and recycle capital."
In addition, historically, during periods of increasing interest rates, real estate valuations have generally decreased as a result of rising capitalization rates, which tend to be positively correlated with interest rates. Consequently, prolonged periods of higher interest rates may negatively impact the valuation of our portfolio and result in the decline of the quoted trading price of our securities and market capitalization, as well as lower sales proceeds from future dispositions. Although the extent of any prolonged periods of higher interest rates remains unknown at this time, negative impacts to our cost of capital may adversely affect our future business plans and growth, including our development and redevelopment activities, at least in the near term.
We have long-term lease agreements with our tenants, and we believe that annual rent escalations within our long-term leases are generally sufficient to offset the effect of inflation on non-recoverable costs, such as general and administrative expenses and interest expense. However, the impact of the current elevated rate of inflation may not be adequately offset by some of our annual rent escalations, and it is possible that the resetting of rents from our renewal and re-leasing activities would not fully offset the impact of the current inflation rate. As a result, during inflationary periods in which the inflation rate exceeds the annual rent escalation percentages within our lease contracts, we may not adequately mitigate the impact of inflation, which may adversely affect our business, financial condition, results of operations, and cash flows.
Additionally, inflation may have a negative effect on the construction costs necessary to complete our development and redevelopment projects, including, but not limited to, costs of construction materials, labor, and services from third-party contractors and suppliers. We rely on a number of third-party suppliers and contractors to supply raw materials, skilled labor, and services for our construction projects. Certain increases in the costs of construction materials can often be managed in our development and redevelopment projects through either general budget contingencies built into our overall construction costs estimates for each of our projects or guaranteed maximum price construction contracts, which stipulate a maximum price for certain construction costs and shift inflation risk to our construction general contractors. However, no assurance can be given that our budget contingencies would accurately account for potential construction cost increases given the current severity of inflation and variety of contributing factors or that our general contractors would be able to absorb such increases in costs and complete our construction projects timely, within budget, or at all.
We have not encountered significant difficulty collaborating with our third-party suppliers and contractors and obtaining materials and skilled labor, and we have not experienced significant delays or increases in overall project costs due to the factors discussed above. While we do not rely on any single supplier or vendor for the majority of our materials and skilled labor, we may experience difficulties obtaining necessary materials from suppliers or vendors whose supply chains might become impacted by economic or political changes, shortages of shipping containers and/or means of transportation, or difficulties obtaining adequate skilled labor from third-party contractors in a tightening labor market. It is uncertain whether we would be able to source the essential commodities, supplies, materials and skilled labor timely or at all without incurring significant costs or delays, particularly during times of economic uncertainty resulting from events outside of our control, including, but not limited to, federal policies and the ongoing or future geopolitical conflicts.
Higher construction costs could adversely impact our investments in real estate assets and expected yields on our development and redevelopment projects, which may make otherwise lucrative investment opportunities less profitable to us. Our reliance on a number of third-party suppliers and contractors may also make such investment opportunities unattainable if we are unable to sufficiently fund our projects due to significant cost increases, or are unable to obtain the resources and materials to do so reasonably due to disrupted supply chains. As a result, our business, financial condition, results of operations, cash flows, liquidity, and ability to satisfy our debt service obligations, and to pay dividends and distributions to security holders could be adversely affected over time.