For multifamily, net applications were up 30% year-over-year in January for our urban properties, and year-to-date trends already reflect improvement in occupancy as we head into the spring leasing season.
Currently, multifamily occupancy is over 95%, excluding our two rent-controlled properties where we are not emphasizing occupancy gains as they offer limited rent growth potential in the current environment.
While multifamily lease rates declined 3.6% and 5.7% on a gross and effective blended basis during the fourth quarter, we believe that December represented the height of rental rate pressure as lease rate changes improved in January on a month-over-month basis and concession declined.
Both urban and suburban renewal lease rate growth increased by 90 basis points during the fourth quarter to 1.7% and 3.1% respectively, and those renewal rate increases remained stable through January.
As a result of the strategic management of our lease expiration schedule, only 20% of our leases expired during the fourth quarter and only 17% expire in the first quarter.
Our forecast indicates that commercial occupancy could increase by nearly 4% by year-end although there is still too much uncertainty to accurately forecast occupancy gains over the course of the year.
For example, in January, we've received the signed LOI from Sunrise Senior Living to renew their space at Silverline, which currently represents approximately 1.5% of office revenue.
Additionally, in January, we signed a 45,000 square foot five-year lease renewal with Giant Food that at Takoma Park, which represents our second largest retail tenant and over 6% of other rental income.
We also signed a 15,000 square foot 10-year lease renewal with our grocery-anchored at Montrose Shopping Center.
These two lease renewals represent approximately 10% of our retail rental income.
The average tenant size in our market and the space requirement that seizes the most volume is about 4,000 to 6,000 square feet, which is both our medium tenant size and the tenant size with the highest demand in the current environment.
Space Plus represents approximately 3% of our office portfolio and is very well positioned once decision-making picks up.
Since the onset of the pandemic, the Washington Metro has benefited from fewer job losses than other major metropolitan areas and has already gained back roughly 180,000 jobs or 56% of the jobs lost from February to May.
Additionally, those job losses have been largely contained to non-office-using sectors as office-using sector employment in the Washington Metro market declined only 2% year-over-year in 2020 according to BLS data.
Over the course of 2020, the tech sector contributed 36% of total leasing volume and more than 800,000 square feet of occupancy growth in Northern Virginia according to CBRE.
Tech-driven leasing demand drove positive absorption for the sector in the fourth quarter and that momentum has continued into January with the announcement of Microsoft's new 180,000 square foot sales headquarters in Rosslyn, next door to Arlington Tower and strategically located at the nexus of four bridges, five major road networks and three metro lines and offers easy access to the Pentagon and Downtown DC.
Government contract awards should remain at record highs in 2021 and the cloud market alone is forecasted to grow 9% to 10% annually over the next three years according to JLL.
Following our fourth quarter office asset sales and including stabilized income from Trove, multifamily comprises 53% of our NOI, while office and retail comprise 41% and 6% respectively.
First, we made sure that we had ample liquidity at the onset of the pandemic by entering into a $150 million one-year term loan with extension rights.
Second, we closed and funded in December a $350 million 10-year Green Bond at 3.44%, and we used the proceeds to pay off the new $150 million term loan and our other $150 million term loan that was scheduled to expire in March of 2021.
In that regard, at year-end, we only had $42 million outstanding on our fully available $700 million line of credit, underscoring that we increased our liquidity further during the pandemic.
We collected 99% of cash and contractual rents during the fourth quarter, and our rent collections through January are in line with our quarterly trend.
We've offered deferred payment programs to residents who've been financially impacted by the pandemic and only a very small amount, about $15,000 of deferred multifamily rent remains outstanding.
We collected 99% of cash rents from office rents -- from office tenants during the fourth quarter and over 99% of contractual rents, which excludes rent that has been deferred.
We deferred rent associated with office tenants and that amount was $1 million as of January 31.
And we expect to collect approximately 75% of that rent that was deferred by year-end with the balance thereafter.
We collected 94% of retail cash rents in the fourth quarter and excluding deferred rent, our collection rate was approximately 97%.
Net deferred rent associated with retail tenants was $1 million as of January 31, 2021 and we expect to collect 40% of that rent at year-end.
Overall, we've only deferred a small portion of rent and the expected cumulative cash NOI impact is less than $0.01 per share through year-end 2021.
Net loss for 2020 was $15.7 million or $0.20 per diluted share, compared to net income of $383.6 million or $4.75 per diluted share in the prior year.
Core FFO of $1.45 per diluted share for full-year 2020 was in line with the midpoint of our guidance range.
On a year-over-year basis, core FFO per share declined by $0.26 due to the strategic transactions completed during 2019 as well as the impact of the pandemic on leasing activity, parking income and credit losses.
Overall, same NOI declined 5.4% year-over-year on a GAAP basis and 4.9% on a cash basis for the full-year 2020.
Multifamily same-store NOI declined 0.9% and 1% on a GAAP and cash basis for the year and 7.2% and 7.3% on a GAAP and cash basis for the fourth quarter.
The full-year and fourth quarter declines were primarily driven by the year-over-year new lease rate declines at our urban assets, which comprise 100% of our same-store portfolio during 2020.
During the fourth quarter, we focused on maintaining occupancy and ended at 94.3%, excluding Trove.
Office same-store NOI declined 7.1% and 6.4% on a GAAP and cash basis for the year and 12.7% on a GAAP and cash basis for the fourth quarter.
Same-store GAAP NOI decreased for our remaining retail centers, which we report as other, by $2.1 million and $1.8 million on a GAAP and cash basis for the year and $0.7 million on a GAAP and cash basis for the fourth quarter.
Overall, commercial credit losses reduced our core FFO by approximately $0.02 per share this quarter, which is higher than the third quarter impact and in line with the second quarter.
Over 60% of the credit losses related to these leases were non-cash straight-line rent write-offs as our cash losses were relatively flat on a sequential basis.
Turning to leasing activity for the fourth quarter and full year, we signed approximately 9,000 square feet of new office leases and 22,000 square feet of office renewals in the fourth quarter.
Office rental rates declined 5% on a GAAP and 9% on a cash basis for new office leases, but increased 22% on a GAAP basis and 8% on a cash basis for office renewals.
Retail signed approximately 8,000 square feet of new leases and 3,000 square feet of renewals during the quarter and achieved rental rate increases of 13% on a GAAP basis for new retail leases and 3% on a GAAP basis for retail renewals.
And as Paul referenced, we signed approximately 60,000 square feet of retail leases, representing 10% of our retail portfolio revenues since year-end.
Starting with multifamily, total operating portfolio occupancy ended the year at 94.3%, which is in line with our expectations and represents a relatively stable trend since the end of the second quarter.
We've increased occupancy to slightly over 95%, excluding our two rent-controlled assets, and we are seeing effective lease rates trending in the right direction.
We expect Trove to add $100,000 of income in the first quarter, ramping up each quarter to approximately $1 billion by the fourth quarter of 2021 with significantly greater growth in 2022 over 2021 levels.
And while we only have a small amount, approximately 20,000 square feet of signed new leases that have not yet rent commenced and approximately 20,000 square feet of signed LOIs for new leases that are expected to rent commence during 2021, we have minimal lease expirations during 2021.
Our 2021 office lease expirations represent less than 3% of our overall revenue.
And we believe that our renewals likely over go [Phonetic] or we are under negotiation for renewal for over 60% of that space.
We have a forecast that can result an occupancy growth of up to 4%, but that forecast is at risk if new leasing is delayed.
For example, that forecast includes a little over $3 million of new leasing revenue in the fourth quarter.
Following the two retail renewals, which were executed in January and which represent 10% of our retail NOI, we have less than 3% of retail revenue expiring in 2021.
Nearly 60% of our current vacancy in Northern Virginia where job growth and absorption rates were the strongest and where we are seeing the most touring and leasing activity.
Our parking garages' capacity can serve over 50% of our building population prior to the pandemic on average, and we still currently have at least 50% parking capacity available, which provides an option for companies that want to encourage employees to return to the office before sentiment improves toward public transportation.
We are guiding to a core FFO per share range of $0.29 to $0.32 per share for the first quarter.
We expect multifamily NOI to range from $20.25 million to $20.75 million, office NOI to range from $17.75 million to $18.5 million and other NOI of approximately $3 million.
G&A is projected to range from $6 million to $6.25 million; interest expense is expected to range from $10 million to $10.25 million; and development expenditures are expected to range from $5 million to $7.5 million.
Since our last earnings call, we sold two office assets and issued approximately 2 million shares through our ATM program at an average price of $23.86 per share to improve our balance sheet and position us to further strengthen our capital allocation once visibility aligns with opportunity to increase multifamily.
Thus we estimate at this time that these two initiatives, net of their interest impact, will further strengthen our balance sheet and lower full-year 2021 core FFO by approximately $0.09 per share.
For the full year, we expect G&A to range from $22.25 million to $23.25 million and interest expense to range from approximately $41.5 million to $42.5 million.
Additionally, assuming that leasing activity and utilization continues to increase and we achieve occupancy growth by year-end, we expect commercial operating expenses to increase by approximately $1 million by the fourth quarter from the first quarter expected range of $11.75 million to $12.25 million.

Summary:
We are guiding to a core FFO per share range of $0.29 to $0.32 per share for the first quarter.